FYI for the pressure gauge I used it did not need a pressure differential to measure the pressure. So that is not the reason it didn’t change. I’ve used this one many times inside my vacuum chamber and it works great.
The presure dosen't play a roll here, beaucause the fridge it's not a seal chamber, there is a smal hole in the fridge to evacuate the water from the auto defreeze function in to a tray in the back of the fridge. I think the seal acts like a momentary spring some how end you gave to overcome that spring force first!
I was able to measure my freezer using an OMRON D6F-PH5050AD4 sensor. I put the result on hackaday. The project title is hrv, and the user is sciencedude1990.
It'd be nice to see the small difference reliably just to be sure we have the right explanation. Ala Steve Mould and Electroboom, explanations can get thorny, the chain link one 🔗🖇️ ahh 😅
@@robbbbery I don't know about that particular unit, but I do know that in the lab where I work we have a -80 C freezer (a LOT colder than a home freezer) that did this when it was new, and it even had a giant screw on the left side that you could unscrew to let air in to break the vacuum. But then as it got older it didn't do this any more, and now it builds up ice inside like cracy, like the other older freezers. I even got service to try to replace the gasket, but that didn't get it back to its new state.
@@MontyCantsin That was the purpose of the giant screw on the left side of our Panasonic Health Care -80 `C freezer where I work, and when it was new, you had to use this to be able to open the door again after closing it. But later on, the seals got bad, and you didn't need to use it, even after we had the seals serviced.
I’m amazed that the interior air temperature drops that quickly. I’ve however experienced this same phenomenon in reverse but when using a microwave oven to heat a dish of food in a food container with a gasketed lid. For example, pop the lid tabs but leave the lid in place, then heat the food as normal and remove the dish from the microwave. Once removed you can then watch the lid concave as its being sucked into what I call a reverse vacuum and it’s impossible to pry the lid apart from the dish without breaking something lol. To remedy, ya gotta put the dish back into the microwave and reheat for 30 seconds or so. To avoid the issue from occurring, you gotta break the seal as you’ve already mentioned by placing a paper towel sheet between the lid and dish, and with the lid in place, your microwave oven’s interior remains clean with no food splatter 😂.
That is mostly due to the water vapor condensing more than the air cooling down. As I mentioned at the end condensations can make crazy changes in pressure almost instantly
The interior of the freezer it self and all the food and frozen stuff in there have way more mass than the volume of air inside and doesn't move by convection and get replaced by warmer mass from outside, like the air. So for the short durations the door is normally open, it will stay at almost the same temperature as it was before the door was opened. Once the door is closed again, all those cold surfaces will very quickly cool down the warmer air that got inside again. I did actually experience the same thing truly in reverse for a big electric furnace that I built for metal/glass melting and stuff (as it was electric, it didn't need an exhaust like a gas furnace and was pretty much like a closed box). Which I made a hole in the front of the door of, to get some ventilation and to be able to watch into it, without the need to open the door every time. That turned out to be quite dangerous. Because every time the door was open, the hot air inside got replaced by cold air from the outside - then when the door was closed again, the air inside heated up quickly and expanded, causing jet of air that was up to 1250°C, to blow out thru that hole, haha.
@@TheActionLabYou can actually measure the pressure drop with the super accurate barometer of your smartphone! There is this free "phyphox" app that lets you log data from the sensors of the phone. I measured it with my fridge, it's about 1.5 hPa pressure drop within 1 second after closing the door. Equilibrating pressure takes another 5 or so seconds.
I agree. This is good channel for uneducated to get already munched up and complete answers without having to use one's head to try and apply pre-existing knowledge on practical setting.
The sheer power of pressure-based suction honestly amazes me, how can such a miniscule drop in pressure as the one in the freezer example create *not only* a noticeable effect, but one that TRIPLES the force required to open the freezer door?
The answer is surface area is multiplicative so what doesn't appear to be a huge change in area actually has a very large effect. Try this same experiment with the smaller freezer door on top of most fridge/freezer units and it is far less noticeable. We also don't seem to think about the actual air pressure very often, probably because it's invisible and we are just so used to it but there is around 6000 miles of atmosphere sitting on us at all times. If you actually start to compare 14.7 PSI atmospheric pressure vs other pressurized systems you realize it's actually a fairly decent amount of force.
Can't remember exactly but it's something like 8-10psi in a house is deadly and will blow your windows out meanwhile you can spray them down with 1500psi pressure washer and do no damage.
Yo so I'm an HVAC tech and I want to thank you for the food for thought with these videos. I swear watching demos like this help me be better at my job 👍🏾👍🏾
A typical refrigerator has a drain hole connected to a pipe that leads to a container where melted ice collects. Most of the time, when the container is not filled with water, the pressure has to equalize much faster because the drain hole is quite large.
You make a good point, air pressure should equalize quickly if that drain tube is not obstructed. If the door is hard to open, I'd inspect and clear that drain of frozen water.
I've noticed that if i slammed shut the big freezer in our basement it was harder to reopen than it was after slowly closing it. So i thought this phenomena was due to the air squished out of the freezer due to the door being shut too kuch for a short time, which then afterwards would cause a lower pressure inside it.
Was it a chest freezer, i.e. with a door on the top? If so, gentle opening will allow the cold air inside to mostly remain inside, since it is heavier than the outside air.
I always liked observing bubbles forming on wine glasses when you place them on the kitchen counter after washing them and before drying. The hot glass heats up the air trapped inside, causing it to expand and "bubble out" to equalize pressure. Once the glass cools down, so will the trapped air, causing it to contract again, creating bubbles, but this time on the inside of the glass
While the pressure drop inside the freezer is small, pressure gauges typically measure relative to their surrounding atmosphere which is why it didn't change when you shut it in the fridge. To get a true idea you'd need to have the gauge outside the fridge with a (well sealed) tube running into the freezer cavity.
That is, unless the meter have it's own sealed pressure chamber to compare against. On one hand, I have no doubt he did know this and used a correct tool properly, one the other, he's made even worse blunders before so it's possible he just made one another.
You can also see this phenomenon if you have a plastic bottle with just some ice inside. If you cover the bottle and shake the ice around, it cools the air inside the bottle and the bottle will begin to compress a bit as the cooling air takes up less volume, reducing the pressure inside. When you open the bottle and allow ambient temperature air to enter, it regains its full shape. Then if you close it and shake it, it compresses a bit again.
I have seen the opposite happen with a bottle of ice water; When I open it after a long, hot day, it will often spray water (just a few mL) into my face, due to the pressure gradient from the air expanding. I only realized what made it do that until now, but it makes perfect sense once you think about it.
I recently stayed at a beach house that had a vacuum sealed Sub Zero refrigerator and that thing was awesome. Of course I'd never pay $15k for a fridge but apparently some people do. It was smart enough to break the seal when you opened the freezer even after closing it.
You can find a similar feature on mid-range fridges these days -- around the $2k price point. They drop the pressure about 20%. I guess the lower the mass of air in there, the easier it is to chill
Would have liked a demo with a non-cooled fridge, running the same open/close test to make more sense and solidify the conclusion, instead of trying to verify the tiny pressure change alone, confirming the conclusion. This would probably rule out? the springy one way rubber seal(bellows?),not adding to the equation. Also, if several trays of hot pastries were let to cool down and see, if that was a terrible mistake?🤯. It might also accidentally, uncover the presence of a hidden one way pressure balancing valve!🧐.Just some 💭♥️👍
If the freezer is not turned on (air inside it is the same temperature as the air in the room), then nothing happens at all. You can open and close it repeatedly without any difficulty on either of them. There's no real point in defrosting a freezer (which clearly has a lot of food inside) just to show something like this.
Following your video, I felt like trying an experiment to see if the door seal had anything to do with it: I thought that maybe when the door is closed, with the speed, the seal is compressed, reducing the air volume between the seal and the fridge edge. The rest, I understood both by watching your video and by trying the experiment. Here is the remaining part of the theory: Furthermore, due to the door opening, the air around the seal was heated; waiting a few seconds after closing the door, the air that remained despite the closing speed became cooled, further reducing the remaining volume. Thus, the pressure between the seal and the door became lower. Due to this low pressure, the seal was pressed even more against the walls, preventing air from passing through. Certainly, after waiting a bit, air enters again partly between the seal and the door, making it easy to open the door again. Here's the experiment I conducted: I opened the fridge door and then closed it very gently. I could reopen the door directly without needing to exert more force. However, if I waited a few seconds after gently closing the door, I couldn't easily reopen it. An astonishing phenomenon: after a gentle closure, even if I reopened and closed it with a bit of speed, I could still reopen it without much effort if I didn't wait. I also tried starting by closing the door with some speed, and I noticed that I could also open the door quite easily (the seal of my fridge probably needs to be replaced :)). So, I think that between the two phenomena I mentioned that could tend to reduce the volume, the one that is most at play is the reduction of air volume due to the decrease in temperature between the seal and the walls of the fridge. The other phenomenon is not to be completely ruled out either; if the door is closed with a lot of speed, it might be more significant.
I think when you close the door slowly the air that is inside is cooling down before the door even closes all the way so the pressure already equilibrates before you even close the door. But when you close it fast it is already completely closed before the air starts to cool down. So when you close it fast there is a larger air difference.
Thanks for the video explaining it. I didn't watch it because I am assuming that the cold air that falls out while the door is open gets replaced by room temp air, which is less dense than cold air. So when the room temp air gets trapped and condenses behind the closed door, the volume of air tries to reduce but is kept from doing so by the rigid structure of the refrigerator, therefore offsetting the equilibrium of the air pressure. A mass of warm air has more volume than the same mass of cold air at equal pressure. Open the air tight door, exchange some cold air for warm, close the air tight door, warm air becomes cold, creating a negative pressure effect.
I love the force measuring apparatus, that was hilarious. I thought he was going to get some scientific instrument that I've never heard of before and then he whips out a scale and paper towel holder.
At 2:25 After the initial theory for why a vacuum was created inside the freezer, I think that the reason could be that the Refrigerator has a One-Way Valve, and that when the refrigerator is closed, the pressure or movement of air from closing the door shut could cause a valve outlet to spin (kind of like a revolving door), that pushes the air out without letting any back in.
I'm so proud of myself for figuring this out myself one afternoon when I experienced this myself while getting a soda can (and then ice) out of my fridge.😂😂
Not sure if it applies to that digital gauge, but usually pressure gauges have to be outside what they are measuring since they use the air they are surrounded by as reference.
I'd be interested to see if he could set up his vacuum chamber with the pressure gauge measuring the outside air. So the spigot is in atmosphere, but the reference portion is in the chamber. What would it show?
@@kutsen39 assuming it's using a reference the way I would expect, it would read an equivalent positive pressure when in vacuum. Would be interesting to see - could compare a digital and mechanical one too.
Mine literally has a button on top that gets depressed when the door is shut. I can turn the light off myself when the fridge is open. Newer fridges probably use a light sensor. Like the type that sends an infrared or some other invisible frequency directly to a detector when closed, and the signal is broken when the door is open, thus triggering the light to turn on.
3:05 I have a slight issue with the way you calculated the pressure difference needed to create that force on the door. Your wooden rod was placed on the door handle of a door that was rotating on a hinge. The force on the door needed to create an equivalent counter torque to prevent the door from rotating will actually be larger than that.
I don't think the point was to get an accurate measure, but more to demonstrate that there was a definite difference, and, at east by that kinda kooky method of measuring it, it took 3 times the force.
@@TheRealDrJoey Yes, fair enough. I just remember him actually calculating the pressure difference necessary to get that force difference, so that's why I mentioned that. I may be mistaken in what he was saying.
@The Action Lab You should have used your phone to measure the pressure difference. There are several apps (my personal favorite is the Physics Toolbox Suite). It actually measures pressure down to Pascals! I've measured the pressure differences when you open doors inside of rooms and push other doors. The pressure difference is usually on the order of 10 Pascals, or up to 50 if you push the door quickly.
Inside the freezer you measure the same pressure as outside as the gummy lips are compressed until the pressure difference is in equilibrium. When you open the door the second time the air cannot flow inside and pressure drops so that it is harder to open.
That is a very good point, the rubber is held tighter to the door due to the vacuum meaning you have to stretch it further to break the seal vs later once pressure has equalized it breaks the seal before stretching very far. I wonder how much of the extras force needed is due to pressure difference and how much is you creating even more pressure difference as you expand the seal? (edit, typo)
I like the way he ran into an issue with his hypothesis when he failed to measure a pressure difference, then proceeded to present a new hypothesis as to why there was no measurement, presenting calculations that proved that the pressure difference was so small that the gauge was not sensitive enough to measure it.
As someone who worked at target I'm very familiar with this the longer the walk in freezer is open the harder it is going to be to open again. that's how that one drunk girl died in the walk in freezer she was too drunk and weak to open it again you really have to put your body into it to open it or just wait for it to get cold again.
We have a -80C (-112F) freezer at work that I semi-frequently use. With such an extreme temperature, it can rise pretty rapidly whenever we open it and we really don't want things inside to get warmer than -75C. Therefore when I'm putting samples in the -80 it'll be like: open freezer -> grab container -> close freezer -> load sample into container-> Open freezer -> put container back. But like the second time I open that motherfucker I have to use my whole body and brace my foot against the pallet it's attached to and it STILL won't open sometimes. This whole time I thought I was crazy, or doing something wrong on the second open, but NO I'm just a victim of physics
When you want to mess with someone mind take a 2 liter pop bottle fill it with very hot water and pore the water out quickly and put the cap on tight. Then set the bottle by them and tell them you are going to crush the bottle with just using your mind. Then about two minutes after you put the cap on the bottle it starts to collapse and goes for a while. It will scare the heck out of someone when the bottle gets mangled and all distorted.
Before watching the rest of the video (only a few seconds in) I'm guessing it has something to do with pressure. Perhaps the warm air that enters the freezer when you open it cools down again after closing it. When this air cools down, the pressure on the inside of the freezer would drop, creating a pressure differential, and therefore a net force pushing the freezer door in. That's my immediate guess upon hearing this problem.
@@stevethorpe I wasn't really thinking about that, but I probably would have figured that the air just slowly leaks through the door and equilibrates. I had no idea there was a mechanical pressure equalizer.
warm air is less dense, then when it replaces the cold air, then all the stuff in the freezer, cools he air, lowering pressure. Good test of freezer door seal!
The same effect occurs when you pour hot tea/coffee in an insulated container and let it cool down. My tea flask makes whistling noises a few minutes after I take a sip because outside air is slipping past the seal and making its way inside
I always thought its just me using up all of my strength to open it the first time and then not having enough for the second one. Thanks for the explaination, now I know everybody can relate
Then the actual answer to the real question is not that the temperature is different, but that the tube mentioned in the video needs time to balance the air pressure on both sides of the door. Because if the high pressure when trying to open the door for the second time was only caused by the air outside the door being warmer than the air inside, the refrigerator would have been difficult to open the first time because the air inside would have gotten colder because it was closed for a long time. I understood that when door is closed for a long time, the tube balances the air pressure outside and inside and opens more easily. And it takes a while to reach this balance.
Just use your phone and phyphox if you don't have a finer gauge. I've measured a pressure drop of about 200 Pa, which should cause about 100 N increase of a force for your freezer, which is very close to your results. Phyphox could plot graphs so you don't need a camera. My phones barometer noise is about 5 Pa, so it's way more sensitive than your gauge.
5:15 That's actually kind interesting, the pressure drop seems to accelerate, I'm guessing it's kind of a chain reaction situation, since lower temperatures means slower movement of molecules they start to slow each other down as each of them slows down.
Respect for the continued quality knowledge drops with organic/quality product ads. You are one of the finest creators on RUclips Cody. Keep improving, growing, and educating the next and previous generations 💎♾️🕊️👊
I really thought a compressor pulled air off, until now thanks for proving me wrong. I was thinking how you would show the gauge inside the freeze, then you put a cam: you also proved that the light of the freezer does not turn off when you close it. 🤣
As a student in Chemistry, this reminds me of breaking a round bottom flask for heating it while plugged. The plug shot out and the flask dropped. Luckily no one was hurt
I was so confused by this title at first. I thought it meant like when you open a freezer for the VERY FIRST time, it's easier to open than every subsequent time. But 15 seconds in and I was like "Ohhhh"
So theoreticly if I have the refrigerator in a room with the same temperature as in the refrigerator and open it, close it and immideatly open it again I would have to make the same force as last time? And again theoreticly if I have the refrigerator in a room with lower temperature as in the refrigerator and open it, close it and immideatly open it again I would have to make even smaller force as last time? Please correct me if I am wrong
After reading the title, and not watching the video, nor ever noticing this effect ever I'd guess the reason is you let in some warm air which then cools, creating a vacuum, which has no time to equalize before you open the door a second time.
It’s the fridge fairies. They like it cold and dark and it annoys them when we open the fridge to flood the space with light and let all the cold out. So, when you try to ope the door again very soon, at least one fridge fairy will be pulling in the other direction, and they are _strong_ little ethereals. But it’s OK, once they get cold enough again, they go straight to sleep.
Scientists may disagree with me but I don’t always say that the air crushes a container. I usually say the inner vacuum crushed it because the way I see it, the changing factor is what does the work. So if you reduce the pressure inside a can, the vacuum does the work but if you increase the outside pressure then it crushes the can. After all if you pull open a door you don't say the outside pressure opens it.
I always thought this phenomenon was because when you open the door, condensation builds on the seals then when you close it, the condensation freezes the two seals together!... I bet this plays a part as well!? 💁♂️🤷♂️
I also wonder why fridge door gasket gets hot. Maybe magnetic gasket and some secret electromagnetic alterations also impact process which you are describing.
I work a liquor store and we have a freezer like that. I always hate when i have to open it twice in a row. I always end up braking the seal at the gasket like you showed.
FYI for the pressure gauge I used it did not need a pressure differential to measure the pressure. So that is not the reason it didn’t change. I’ve used this one many times inside my vacuum chamber and it works great.
The presure dosen't play a roll here, beaucause the fridge it's not a seal chamber, there is a smal hole in the fridge to evacuate the water from the auto defreeze function in to a tray in the back of the fridge. I think the seal acts like a momentary spring some how end you gave to overcome that spring force first!
I was able to measure my freezer using an OMRON D6F-PH5050AD4 sensor. I put the result on hackaday. The project title is hrv, and the user is sciencedude1990.
@@edyeduard4368 Spring force?...
@@edyeduard4368did you watch the video? Not like in a rude way, you seem to be telling him what he said in the start of the video
It'd be nice to see the small difference reliably just to be sure we have the right explanation. Ala Steve Mould and Electroboom, explanations can get thorny, the chain link one 🔗🖇️ ahh 😅
If your freezer DOESN'T do this, it probably means the seal is bad, and it is wasting energy due to warm air entering all the time.
Uh oh, mine doesn't! Did older freezers do it? I don't remember noticing it growing up, only as an adult.
@@robbbbery I don't know about that particular unit, but I do know that in the lab where I work we have a -80 C freezer (a LOT colder than a home freezer) that did this when it was new, and it even had a giant screw on the left side that you could unscrew to let air in to break the vacuum. But then as it got older it didn't do this any more, and now it builds up ice inside like cracy, like the other older freezers. I even got service to try to replace the gasket, but that didn't get it back to its new state.
Yeah, even my freezer has this problem. It's quite old, though.
Or you have a good valve connecting the inside to the outside
@@MontyCantsin That was the purpose of the giant screw on the left side of our Panasonic Health Care -80 `C freezer where I work, and when it was new, you had to use this to be able to open the door again after closing it. But later on, the seals got bad, and you didn't need to use it, even after we had the seals serviced.
This seems like a vid someone would make during the pandemic. Trapped at home, looks around their flat, "Okay... what science can I do HERE?"
People like action lab are the people that lead to the greatest inventions...from their "flat"
Well maybe but science is all around us🙂
Flashbacks 💀💥💥💥
😂😂😂
@@towerofresonance4877yeah I'm with you on the "flat" who says flat? Fuckin British man.
I’m amazed that the interior air temperature drops that quickly.
I’ve however experienced this same phenomenon in reverse but when using a microwave oven to heat a dish of food in a food container with a gasketed lid. For example, pop the lid tabs but leave the lid in place, then heat the food as normal and remove the dish from the microwave. Once removed you can then watch the lid concave as its being sucked into what I call a reverse vacuum and it’s impossible to pry the lid apart from the dish without breaking something lol. To remedy, ya gotta put the dish back into the microwave and reheat for 30 seconds or so.
To avoid the issue from occurring, you gotta break the seal as you’ve already mentioned by placing a paper towel sheet between the lid and dish, and with the lid in place, your microwave oven’s interior remains clean with no food splatter 😂.
That is mostly due to the water vapor condensing more than the air cooling down. As I mentioned at the end condensations can make crazy changes in pressure almost instantly
The interior of the freezer it self and all the food and frozen stuff in there have way more mass than the volume of air inside and doesn't move by convection and get replaced by warmer mass from outside, like the air. So for the short durations the door is normally open, it will stay at almost the same temperature as it was before the door was opened. Once the door is closed again, all those cold surfaces will very quickly cool down the warmer air that got inside again.
I did actually experience the same thing truly in reverse for a big electric furnace that I built for metal/glass melting and stuff (as it was electric, it didn't need an exhaust like a gas furnace and was pretty much like a closed box). Which I made a hole in the front of the door of, to get some ventilation and to be able to watch into it, without the need to open the door every time. That turned out to be quite dangerous. Because every time the door was open, the hot air inside got replaced by cold air from the outside - then when the door was closed again, the air inside heated up quickly and expanded, causing jet of air that was up to 1250°C, to blow out thru that hole, haha.
@@TheActionLabYou can actually measure the pressure drop with the super accurate barometer of your smartphone! There is this free "phyphox" app that lets you log data from the sensors of the phone. I measured it with my fridge, it's about 1.5 hPa pressure drop within 1 second after closing the door. Equilibrating pressure takes another 5 or so seconds.
@@Speeder84XL Sounds like fun times 😁😅
@@TheActionLab I think the Bernoulli effect also plays a major role where closing the door forces some air out before it shuts completely.
I love how The Action Lab makes videos answering questions that we were asking ourselves in our minds before.
Thanks man!
I agree. This is good channel for uneducated to get already munched up and complete answers without having to use one's head to try and apply pre-existing knowledge on practical setting.
The sheer power of pressure-based suction honestly amazes me, how can such a miniscule drop in pressure as the one in the freezer example create *not only* a noticeable effect, but one that TRIPLES the force required to open the freezer door?
The answer is surface area is multiplicative so what doesn't appear to be a huge change in area actually has a very large effect. Try this same experiment with the smaller freezer door on top of most fridge/freezer units and it is far less noticeable.
We also don't seem to think about the actual air pressure very often, probably because it's invisible and we are just so used to it but there is around 6000 miles of atmosphere sitting on us at all times. If you actually start to compare 14.7 PSI atmospheric pressure vs other pressurized systems you realize it's actually a fairly decent amount of force.
Can't remember exactly but it's something like 8-10psi in a house is deadly and will blow your windows out meanwhile you can spray them down with 1500psi pressure washer and do no damage.
Yo so I'm an HVAC tech and I want to thank you for the food for thought with these videos. I swear watching demos like this help me be better at my job 👍🏾👍🏾
A typical refrigerator has a drain hole connected to a pipe that leads to a container where melted ice collects. Most of the time, when the container is not filled with water, the pressure has to equalize much faster because the drain hole is quite large.
You make a good point, air pressure should equalize quickly if that drain tube is not obstructed. If the door is hard to open, I'd inspect and clear that drain of frozen water.
My fridge’s drain hole turned out clogged. After cleaning it, it’s much easier to open the door.
I've noticed that if i slammed shut the big freezer in our basement it was harder to reopen than it was after slowly closing it. So i thought this phenomena was due to the air squished out of the freezer due to the door being shut too kuch for a short time, which then afterwards would cause a lower pressure inside it.
I wonder if slamming the door forced some air through the equilibration tube while slowly closing the door didn't. Good observation!
Was it a chest freezer, i.e. with a door on the top? If so, gentle opening will allow the cold air inside to mostly remain inside, since it is heavier than the outside air.
@@MontyCantsin yes it is, and this actually makes a lot of sence now.
I always liked observing bubbles forming on wine glasses when you place them on the kitchen counter after washing them and before drying. The hot glass heats up the air trapped inside, causing it to expand and "bubble out" to equalize pressure. Once the glass cools down, so will the trapped air, causing it to contract again, creating bubbles, but this time on the inside of the glass
Once in a while I do that to a plate, completely by accident, and it starts making noise from the bubbles and sliding along the table.
While the pressure drop inside the freezer is small, pressure gauges typically measure relative to their surrounding atmosphere which is why it didn't change when you shut it in the fridge. To get a true idea you'd need to have the gauge outside the fridge with a (well sealed) tube running into the freezer cavity.
That is, unless the meter have it's own sealed pressure chamber to compare against.
On one hand, I have no doubt he did know this and used a correct tool properly, one the other, he's made even worse blunders before so it's possible he just made one another.
You can also see this phenomenon if you have a plastic bottle with just some ice inside. If you cover the bottle and shake the ice around, it cools the air inside the bottle and the bottle will begin to compress a bit as the cooling air takes up less volume, reducing the pressure inside. When you open the bottle and allow ambient temperature air to enter, it regains its full shape. Then if you close it and shake it, it compresses a bit again.
I have seen the opposite happen with a bottle of ice water; When I open it after a long, hot day, it will often spray water (just a few mL) into my face, due to the pressure gradient from the air expanding. I only realized what made it do that until now, but it makes perfect sense once you think about it.
@@alexandermcclure6185with me recently getting an insulated tumbler, yea this happens frequently too lol
I recently stayed at a beach house that had a vacuum sealed Sub Zero refrigerator and that thing was awesome. Of course I'd never pay $15k for a fridge but apparently some people do. It was smart enough to break the seal when you opened the freezer even after closing it.
You can find a similar feature on mid-range fridges these days -- around the $2k price point. They drop the pressure about 20%. I guess the lower the mass of air in there, the easier it is to chill
I’ve gone my entire life just thinking I was significantly weaker on the second pull 😂😅 great explainer video!
there's no way you actually thought that right?
@@jonathanc2536 🤣😂 there’s no way you actually thought I thought that right?
@@leafy_5there’s no way you actually thought that he thought you thought that right?
@@raqqafeller152 there's no way you thought that he thought that he thought that he thought that, right?
Both can be and are true. 🫠
Would have liked a demo with a non-cooled fridge, running the same open/close test to make more sense and solidify the conclusion, instead of trying to verify the tiny pressure change alone, confirming the conclusion. This would probably rule out? the springy one way rubber seal(bellows?),not adding to the equation. Also, if several trays of hot pastries were let to cool down and see, if that was a terrible mistake?🤯. It might also accidentally, uncover the presence of a hidden one way pressure balancing valve!🧐.Just some 💭♥️👍
If the freezer is not turned on (air inside it is the same temperature as the air in the room), then nothing happens at all. You can open and close it repeatedly without any difficulty on either of them. There's no real point in defrosting a freezer (which clearly has a lot of food inside) just to show something like this.
@@kikixchannel Finding an empty fridge(any appliance showroom should have many!) should be easier than acquiring a bottle of liquid nitrogen🤔
ik so love the placement of your sponsors! i will not skip yours like i do so many others
much Appreciated!
Thanks for answering the question. Kinda had an idea that it worked that way. Always wondered what made the door get sucked in and the noise it made.
one of my freezers won't do that until l adjust the seal on the bottom of the door, it works best when it gets that seal
It's stronger because the photons from inside the fridge light don't want you to know it'll turn off.
The can made me think of the imploded sub. The speed is insane!
THIS MAN BE GIVING THE ANSWERS TO THE QUESTIONS WE ALL SECRETLY WANNA KNOW
Following your video, I felt like trying an experiment to see if the door seal had anything to do with it:
I thought that maybe when the door is closed, with the speed, the seal is compressed, reducing the air volume between the seal and the fridge edge.
The rest, I understood both by watching your video and by trying the experiment. Here is the remaining part of the theory:
Furthermore, due to the door opening, the air around the seal was heated; waiting a few seconds after closing the door, the air that remained despite the closing speed became cooled, further reducing the remaining volume.
Thus, the pressure between the seal and the door became lower. Due to this low pressure, the seal was pressed even more against the walls, preventing air from passing through.
Certainly, after waiting a bit, air enters again partly between the seal and the door, making it easy to open the door again.
Here's the experiment I conducted: I opened the fridge door and then closed it very gently. I could reopen the door directly without needing to exert more force. However, if I waited a few seconds after gently closing the door, I couldn't easily reopen it. An astonishing phenomenon: after a gentle closure, even if I reopened and closed it with a bit of speed, I could still reopen it without much effort if I didn't wait.
I also tried starting by closing the door with some speed, and I noticed that I could also open the door quite easily (the seal of my fridge probably needs to be replaced :)).
So, I think that between the two phenomena I mentioned that could tend to reduce the volume, the one that is most at play is the reduction of air volume due to the decrease in temperature between the seal and the walls of the fridge. The other phenomenon is not to be completely ruled out either; if the door is closed with a lot of speed, it might be more significant.
I think when you close the door slowly the air that is inside is cooling down before the door even closes all the way so the pressure already equilibrates before you even close the door. But when you close it fast it is already completely closed before the air starts to cool down. So when you close it fast there is a larger air difference.
Thanks for the video explaining it. I didn't watch it because I am assuming that the cold air that falls out while the door is open gets replaced by room temp air, which is less dense than cold air. So when the room temp air gets trapped and condenses behind the closed door, the volume of air tries to reduce but is kept from doing so by the rigid structure of the refrigerator, therefore offsetting the equilibrium of the air pressure.
A mass of warm air has more volume than the same mass of cold air at equal pressure. Open the air tight door, exchange some cold air for warm, close the air tight door, warm air becomes cold, creating a negative pressure effect.
I love the force measuring apparatus, that was hilarious.
I thought he was going to get some scientific instrument that I've never heard of before and then he whips out a scale and paper towel holder.
If you think that’s funny, wait until I tell you it was a plunger!
There's a reason commercial walk-in freezers have a heated (so frost doesn't develop on it and freeze it) two pressure relief baffle system.
At 2:25
After the initial theory for why a vacuum was created inside the freezer, I think that the reason could be that the Refrigerator has a One-Way Valve, and that when the refrigerator is closed, the pressure or movement of air from closing the door shut could cause a valve outlet to spin (kind of like a revolving door), that pushes the air out without letting any back in.
This should testable with a warm or not running freezer
I'm so proud of myself for figuring this out myself one afternoon when I experienced this myself while getting a soda can (and then ice) out of my fridge.😂😂
Not sure if it applies to that digital gauge, but usually pressure gauges have to be outside what they are measuring since they use the air they are surrounded by as reference.
I'd be interested to see if he could set up his vacuum chamber with the pressure gauge measuring the outside air. So the spigot is in atmosphere, but the reference portion is in the chamber. What would it show?
@@kutsen39 assuming it's using a reference the way I would expect, it would read an equivalent positive pressure when in vacuum. Would be interesting to see - could compare a digital and mechanical one too.
That power generator/battery was really cool. But I would never use it.
It has all of these cool features but I might use it once a year😂
Nice, now could you please explain if the light goes out when you close the door or not?
It goes out, like older fridges had a v like trigger at the time. My current one has a sensor so ifyou line the doors up when open it'll turn off
There is a little guy in the freezer that turns off the light when he sees you close the door
Lol.ive tried to catch mine on,but its to sneeky.🤔
@@mr_dadik lol
Mine literally has a button on top that gets depressed when the door is shut. I can turn the light off myself when the fridge is open. Newer fridges probably use a light sensor. Like the type that sends an infrared or some other invisible frequency directly to a detector when closed, and the signal is broken when the door is open, thus triggering the light to turn on.
I asked about this in the comments at another video, years ago. This is a great answer
I've been wondering about this for many years. Thank you for answering it.
Same here my friend
So, no second beer genius in there!!
yeah! finally, you got to do a video about this, I've always suspected this but never experimented it
0:18 i remember touching some part of fridge and it was super hot… it was somewhere near that. Im never touching weird places again.
1:50 yor pressure gauge is not sensitive enough. You could have used your barometer in your smartphone. They are way more sensitive.
I am glad I'm not a fool. I also experienced it .... I thought I was the only one who experienced it.
I always needed to know this.. thanks bud 🎉
RUclips: He watches anything anything at this point
This is actually an interesting video.
wow great price on the solar charger and love how fast it charges
Great video. Perfect illustration for a daily situation.
3:05 I have a slight issue with the way you calculated the pressure difference needed to create that force on the door. Your wooden rod was placed on the door handle of a door that was rotating on a hinge. The force on the door needed to create an equivalent counter torque to prevent the door from rotating will actually be larger than that.
Jesus, get yourself a girlfriend or go Mountain-biking ASAP!
@@IIISentorIII This is literally a channel by and for physics nerds.
@@IIISentorIII No thanks
I don't think the point was to get an accurate measure, but more to demonstrate that there was a definite difference, and, at east by that kinda kooky method of measuring it, it took 3 times the force.
@@TheRealDrJoey Yes, fair enough. I just remember him actually calculating the pressure difference necessary to get that force difference, so that's why I mentioned that. I may be mistaken in what he was saying.
We'd like to thank our sponsors Eggo Waffles, Creamies ice cream, and Kirkland shredded cheese (which I guess is OK to freeze).
Frozen shredded cheese never seems to thaw well for me
Oh, thanks for explaining! I observed this effect and although I was annoyed by it, I didn't realize what's going on.
I love this channel.... been watching it for years! Thank you!
@The Action Lab You should have used your phone to measure the pressure difference. There are several apps (my personal favorite is the Physics Toolbox Suite). It actually measures pressure down to Pascals!
I've measured the pressure differences when you open doors inside of rooms and push other doors. The pressure difference is usually on the order of 10 Pascals, or up to 50 if you push the door quickly.
Just tried the physics toolbox suite and it’s awesome. Had no idea my phone could make all these measurements so precisely.
Thanks for sharing.
@@cyrilio Yes, it's amazing! Glad you found it! :)
No barometer sensor on my phone ☹️
@@jasonharrison25 If you get another phone, most of the newer ones have it. It doesn't even have to be very new; it can be from 5 years ago.
I notice that effect with my refrigerator also. I wondered why. Now i know. Thanks.
Inside the freezer you measure the same pressure as outside as the gummy lips are compressed until the pressure difference is in equilibrium. When you open the door the second time the air cannot flow inside and pressure drops so that it is harder to open.
That is a very good point, the rubber is held tighter to the door due to the vacuum meaning you have to stretch it further to break the seal vs later once pressure has equalized it breaks the seal before stretching very far. I wonder how much of the extras force needed is due to pressure difference and how much is you creating even more pressure difference as you expand the seal?
(edit, typo)
I like the way he ran into an issue with his hypothesis when he failed to measure a pressure difference, then proceeded to present a new hypothesis as to why there was no measurement, presenting calculations that proved that the pressure difference was so small that the gauge was not sensitive enough to measure it.
Vacuum caused by the warm air losing volume by being chilled. Over time, the vacuum is lost due to imperfect seals.
I never had a freezer so I didn't know about this but I realized why this happens pretty quickly after I saw the title. Low-key proud hehe
OMG! Loved the plunger and scale. Your the best.
"why is it harder the second time?"
my dirty mind💀
As someone who worked at target I'm very familiar with this the longer the walk in freezer is open the harder it is going to be to open again. that's how that one drunk girl died in the walk in freezer she was too drunk and weak to open it again you really have to put your body into it to open it or just wait for it to get cold again.
You should have used a samrtphone's barometer to measure the pressure difference, they're incredibly accurate
Really good demonstration. I have wondered about this phenomena for some time now.
thank you for answering all these questions!!!
Thank you, I always wondered what was happening.
We have a -80C (-112F) freezer at work that I semi-frequently use. With such an extreme temperature, it can rise pretty rapidly whenever we open it and we really don't want things inside to get warmer than -75C. Therefore when I'm putting samples in the -80 it'll be like: open freezer -> grab container -> close freezer -> load sample into container-> Open freezer -> put container back. But like the second time I open that motherfucker I have to use my whole body and brace my foot against the pallet it's attached to and it STILL won't open sometimes. This whole time I thought I was crazy, or doing something wrong on the second open, but NO I'm just a victim of physics
aren't we all victims of physics though? 😥😥
When you want to mess with someone mind take a 2 liter pop bottle fill it with very hot water and pore the water out quickly and put the cap on tight. Then set the bottle by them and tell them you are going to crush the bottle with just using your mind. Then about two minutes after you put the cap on the bottle it starts to collapse and goes for a while.
It will scare the heck out of someone when the bottle gets mangled and all distorted.
Some laboratory deep freezers have a vent. When you close the door, you can hear the air rush in.
Wow you explained it really well even better than some teachers at my school
Before watching the rest of the video (only a few seconds in) I'm guessing it has something to do with pressure. Perhaps the warm air that enters the freezer when you open it cools down again after closing it. When this air cools down, the pressure on the inside of the freezer would drop, creating a pressure differential, and therefore a net force pushing the freezer door in. That's my immediate guess upon hearing this problem.
But did you also guess why it becomes easier again, for the next time you feel like a quick snack 😄
@@stevethorpe I wasn't really thinking about that, but I probably would have figured that the air just slowly leaks through the door and equilibrates. I had no idea there was a mechanical pressure equalizer.
My daughter is always moaning how hard the freezer door is to open as if it's my fault. Thanks for this, I'll be showing her this immediately.
Thank you so much for this video .32!years of wondering
I thought it was just my imagination that it was harder to open it the second time. Finally someone is explaining it.
that's INSANE!
Such a tiny change for such a large difference!
warm air is less dense, then when it replaces the cold air, then all the stuff in the freezer, cools he air, lowering pressure. Good test of freezer door seal!
The same effect occurs when you pour hot tea/coffee in an insulated container and let it cool down.
My tea flask makes whistling noises a few minutes after I take a sip because outside air is slipping past the seal and making its way inside
Amazing how I just now noticed it for the first time in my life and then exactly after I stumbled upon this video.
I've always wondered this! Also, TIL: "equilibrates"
I always thought its just me using up all of my strength to open it the first time and then not having enough for the second one. Thanks for the explaination, now I know everybody can relate
I’ve always wondered about this! Thanks!! 😃
Then the actual answer to the real question is not that the temperature is different, but that the tube mentioned in the video needs time to balance the air pressure on both sides of the door. Because if the high pressure when trying to open the door for the second time was only caused by the air outside the door being warmer than the air inside, the refrigerator would have been difficult to open the first time because the air inside would have gotten colder because it was closed for a long time. I understood that when door is closed for a long time, the tube balances the air pressure outside and inside and opens more easily. And it takes a while to reach this balance.
Without the video even starting I know it’s because of pressure, and if it’s hard you just push in before pulling. Works so well
That was great. I'm wondering about the online pressure simulators you were talking about. Can you provide some site info please? Thanks
Just use your phone and phyphox if you don't have a finer gauge. I've measured a pressure drop of about 200 Pa, which should cause about 100 N increase of a force for your freezer, which is very close to your results. Phyphox could plot graphs so you don't need a camera. My phones barometer noise is about 5 Pa, so it's way more sensitive than your gauge.
The vacuum seal seems to be in good condition but if bad condition the door won’t open properly
5:15
That's actually kind interesting, the pressure drop seems to accelerate, I'm guessing it's kind of a chain reaction situation, since lower temperatures means slower movement of molecules they start to slow each other down as each of them slows down.
I have always had this question.
Yes. This happened to me like 3 days ago. Thank you.
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His name is James. He does look like a Cody to me as well.
Pretty sure the condensation was from water vapor, not oxygen.
I really thought a compressor pulled air off, until now thanks for proving me wrong.
I was thinking how you would show the gauge inside the freeze, then you put a cam: you also proved that the light of the freezer does not turn off when you close it. 🤣
thanks for putting that rock back
As a student in Chemistry, this reminds me of breaking a round bottom flask for heating it while plugged. The plug shot out and the flask dropped. Luckily no one was hurt
I was so confused by this title at first. I thought it meant like when you open a freezer for the VERY FIRST time, it's easier to open than every subsequent time.
But 15 seconds in and I was like "Ohhhh"
The condition of the rubber can also affect the seal of the freezer, if it's old and deteriorated it will not seal that hard.
for some reason, the scale + stick pressure gauge impressed me the most.
So theoreticly if I have the refrigerator in a room with the same temperature as in the refrigerator and open it, close it and immideatly open it again I would have to make the same force as last time?
And again theoreticly if I have the refrigerator in a room with lower temperature as in the refrigerator and open it, close it and immideatly open it again I would have to make even smaller force as last time?
Please correct me if I am wrong
After reading the title, and not watching the video, nor ever noticing this effect ever I'd guess the reason is you let in some warm air which then cools, creating a vacuum, which has no time to equalize before you open the door a second time.
It’s the fridge fairies. They like it cold and dark and it annoys them when we open the fridge to flood the space with light and let all the cold out. So, when you try to ope the door again very soon, at least one fridge fairy will be pulling in the other direction, and they are _strong_ little ethereals. But it’s OK, once they get cold enough again, they go straight to sleep.
Scientists may disagree with me but I don’t always say that the air crushes a container. I usually say the inner vacuum crushed it because the way I see it, the changing factor is what does the work. So if you reduce the pressure inside a can, the vacuum does the work but if you increase the outside pressure then it crushes the can. After all if you pull open a door you don't say the outside pressure opens it.
I always thought this phenomenon was because when you open the door, condensation builds on the seals then when you close it, the condensation freezes the two seals together!... I bet this plays a part as well!? 💁♂️🤷♂️
I also wonder why fridge door gasket gets hot. Maybe magnetic gasket and some secret electromagnetic alterations also impact process which you are describing.
If the gasket freezes, you won't be able to open the door.
I didn't notice that it's harder second time
But noticed that. But sometimes notice that it's hard to open sometime
This whole time I thought it was just the fridge I've been using
The moisture in the air condenses on the interior, there are literally less molecules floating around in your freezer creating the vacuum.
I have never seen this before, with any freezers I have had, or had seen at a friends house(not that I open and close my friends freezer) before.
I work a liquor store and we have a freezer like that. I always hate when i have to open it twice in a row. I always end up braking the seal at the gasket like you showed.