Yeah We are your Beloved Viewer.. Have a nice day sir, We are still friends... rather friendship is getting stronger with more and more lectures.. and Problem of the Weeks...
I am just a normal person with no College education I love doing the different experiments each week i truly hope you keep them up I did this one what I have found is two different ways of doing this in a different way 1 is not to turn the bottles all the way up but keep them at a angle 2 and the most effective way I found is to fill a sink up with hot water them turning it upside down in the hot water the gases over power the surface tension of the water in the bottles my best time was 16 seconds thanks so much
About two weeks ago I finished watching all Yours 8.0x lectures with great pleasure. Thank You for all these lectures and great experiments. I was very good in math and physics during my education, but I learn a lot new things and saw explanation for many things that I knew that exist, but did not know what is really happened. So, said that, I saw this in one of Yours lectures, so I will not give solution here, it is simple but not so intuitive at first moment. Best regards from Srbija.
I think the fastest way is to first flip bottles just like you did so gravity will do the work and then constantly shake top bottle in circles because than water will crate spiral and it will fall faster. I didn't try it yet but i think that it will be about 2 times slower (about 30-45 seconds). Thanks for still making videos at this age and helping kids and young people learn physics in a fun way with really good professor!
I started with watching your lectures just yesterday and now am so much loving ur lectures that I started watching from ur problem 1 ..read about rattle back now going to make the setup in problem 2. You are that brilliant teacher any student would wish of
Without carry out experiment, I can think of starting with Bottles align parallel to Earth Sufrace, then further rotating for next 90-deg with appropriate speed that liguid Flow does not block.
Dear Dr. Lewin, Love your style of teaching, it is informative and entertaining at the same time. You are to be commended for all the countless viewers that you have inspired. In your last video on the subject of the lemonade transfer problem, you made mention of possibly entertaining suggestions for 'interesting' physics problems. While perhaps a bit too esoteric, the two capacitor paradox is one that causes many to scratch their heads trying to explain the results. I have had fun with this one in my engineering circles on many occasions. There are so many different approaches and nearly as many analogs to the paradox that it could spark up some interesting exchanges.
Hey Dr Walter, Sorry, I have not done the experiment so, I do not have any duration but I have a theory. The "problem" is after the set up, the system is at equilibrium (same pressure, temperature and volume). When you flipped the system and gravity starts pulling on water, the more water goes to the second bottle, the more pressurized it becomes because the volume taken by air is decreasing. The exact opposite happens to the bottle on top. This prevents water from transferring as fast as it can because there is always a force going from high to low pressure. So, my solution is that before and while water is transferring, the top battle can be heated to increase the pressure (but not as much to melt the bottle) and the bottle below can be placed in ice to low the pressure. Then, the transfer time should be much lower.
by constantly shaking we might transfer lemon juice little faster. i done similar thing before, it took around 1 min. to transfer.... tnx Mr. physics for these kind of puzzles and questions.
Professor, Honestly i made myself a big fan of yours intelligence.. And i ve downloaded your classical physics and electricity and magnetism and this is what i do.. i will take a note of everything what you say in those lectures as your students do in your class.. And i really really loved physics after seeing your lectures and videos..In fact i have a folder in my computer as Walter Lewin..
Hello Dr Lewin, sorry to have kept you waiting, was preparing for my Skippers Exam in the Netherlands. To cause of this problem is clearly a battle between surface tension, partial vacuum in the top bottle and gravity. When left alone surface tension will Wim and form a stable small surface in the part that connects both bottles. as I cannot enter a soap, I must return to physics. So I need to enter another factor to destabilise the surface. I guess swirling will be effective. It prevents a surface building up. Does remind me of my student days back in '77. My graduation project in chemical engineering dealt with the Marangoni effect. Example: evaporating alcohol from liquor will cause drops to build on the glass which creep up before falling down in the rest of the fluid. Keep up the good work. I enjoy these very much, groeten uit Leeuwarden, NL
Hello, I think the best way to do it is to squeeze the upper bottle, hence pressurizing the lower one and taking some liquid with it. After some time you have to squeeze the lower bottle to force some air to the upper bottle. Then you start from the beginning. The exact time depends on how handy a person is and what kind of bottle that is, but it can be done in a few seconds only.
I haven't made the dual-bottle thing, but I'll use yours. That is, in my head. I start with compressing the top bottle so that most of the air will be in the half-filled bottle. When I now turn the whole thing upside down, the fluid will *rocket* down, and I guess it will take around five seconds.
I got it First we will reverse the bottle where the filled bottle will be on top and empty bottle at the bottom... Then we will squeeze the empty bottle and leave it ...The water will start filling faster due to pressure....and repeat the process until the bottle at the top is empty.... honestly I assumed it by my own.....becz I noticed it when I used to fill bottle in my childhood and to complete my work faster I discovered this technique....
I just connected two bottles and sealed them with seal tape, I taped a straw to the inside of the bottles' necks, one end of the straw goes deep in the bottle containing the water and the other end of the straw is at the top of the bottle being filled and it took me just less than 4 seconds to transfer one liter of water.
Just pass a straw between two bottle necks such that one end of the straw is in the empty bottle and near to the neck and other end of straw to the deep inside the filled bottle so that when the bottle gets tilted upside down both ends of the straw will be in air. As a result of that air will pass through straw smoothly and lemonade will pass through the bottle joint. Sorry I will not be able to make a model to get the answer practically, but I can do it theoretically by knowing some values like lemonade density, straw diameter, bottle neck diameter etc. You are an artist sir, I get a lot of help in physics from your videos.
Sir I intended to pass that straw from inside of the two bottles, maintaining the isolated system, so that air pass from one bottle to other. And are you suggesting to take air from outside, because that's against the rule. Another video of Walter sir indicated that rule to not to punch a hole in bottle. Or I failed to get your concept???
So, I built this thing. I cut open 2 caps, put one bottle with 1 liter water in the freezer. put the other bottle in the oven at 50 C only. After one hour ( water cold but not frozen ) i taped upper and lower bottle together ( with cut open caps on to give the tape some surface ) and turned it over. Transfer was done in about 6 seconds. So I thought i figured it out. Then i turned it over the next day, all at room temperature .... transfer took about 7 seconds. Apparently, in my case, temperatures do not matter much. Then i spotted a difference with prof. Lewins video. My water comes down on the plastic inner surface of the lower bottle , wo exception, in a more or less smooth way unlike Prof. Lewins video. My conclusion it that the surface roughness inside of the connection between the bottles makes all the difference. If it is rough it will soak up and attract the water, which makes it pass on the outside. The air in turn will take the center to flow. This way the two flows are not opposing each other and upper and lower surface pressure will not stabilize equal, causing it to not stop and flow fast.
Sorry, but i don't think you understand correctly. The caps are just part of the tunnel and airtight to the outside. I just made a round hole in the top and they are only there to have a good surface for the tape. I could just have taped the threads together, i think with simular results. However, I sense my answer is not the one your looking for. I'm eager to hear you explanation My tunnel is also shorter than yours. I hope the problems keep coming :-) These are fun. I understand how hard it is though to come up with something original
At a point, the weight of the water+some air above it in top bottle is equal to the pressure of the air in the bottom bottle. This air in the bottom bottle has to be displaced by the water from top bottle. Put a small hole at the top of the bottom bottle so that the air from the bottom bottle escapes out and water takes its place.
You're a very entertaining teacher, I was sad when I realised I didn't have enough understanding to make use of your lectures. This problem looks to much like the Jerry can problem. A smaller hole was added to the back of a jerry can to stop the gurgling, hole was a lot smaller than the pour hole as the difference in density. I would start with making the tunnel as clear as possible and have a straw sticking 6 inches into either bottle for the air passage. The fact that your fluid stopped makes me think you have some trickery in your tunnel
I am sorry that I am posting this comment before doing the experiment but I feel that along with gravity, we must also allow pressure to do the work, as it is a closed system. So, my idea is to just press the bottle on the bottom when the system is made upside down. I feel that this may take well below 10 seconds, if done with proper practise and good technique.
Squeeze and release. the bottom bottle. Is that allowed? The restriction is caused by the constant increase in pressure in the lower bottle and the decrease of pressure in the upper bottle as the liquid transfers. This eventually causes the air to be forced up to the upper bottle. A little squeeze of the lower bottle forces the air up, and "above" the liquid, increasing the pressure in the upper bottle, then the release of the lower one, lowers the pressure in that one and the liquid is forced under pressure into the lower bottle. It's basic pressure/ flow rate physics. The same process can be applied to electrons stored in a capacitor.
Turn the bottle upside down and the one with lemonade should be squeezed because of which pressure is built and takes almost up to 10 to 15 seconds for the lemonade to gush out
warmup the empty container. this would cause the air to expand. then get the bottles connected. when the empty bottle cools down a vacuum exist in it. invert the system. this method will ease the flow since high pressure would exist on the lemonade when inverted. this would increase the velocity of flow. thereby decreasing the time.
I have at least three options: the first one is to put this construction horizontally to produce a free transfer of liquid and air inside; the second one is to do the same thing like it's shown in this video but with squeezing a bottle on top to produce greater acceleration of the liquid inside; the third option is to just shake the whole construction. All my other options are just some combinations of these three opportunities. I guess I'll try them tomorrow.
But what if I give some extra acceleration by just moving this construction up supper fast? Not just shaking it up and down (I used the wrong word when I described the third option). I guess it may give an extra acceleration which depends only on how fast I can do it. If I do it supper fast can this option become the winner?
i think by broaden the tuneel between the two bottles and making another way of conection between the two bottles so the air transefer when the liquid takes place
Sir, there are two solutions, 1.Make a hole in both bottles where there is air , the water will move quickly because the air resisting its flow will out from the hole in lower bottle due to increasing pressure and move inward in the upperbottle where pressure is decreasing. 2. make the bottle horizontal so that the space in the tunnel is somewhat occupied by the lemonade and rest empty ,and then slowly tilt it so that there is always space for air to travel from one bottle to other.
hii i m swadhin . thnx for your lectures sir. i m a great fan of your. let me solve this first....... sir u have to do just following things: 01.make the bottle-system horizontal with the force of gravity. 02. now slowly tilt it towards the empty one. 03.then your favorite lemon juice will start going towards empty one. 03.increase the slope of the bottle-system slowly and try to avoid formation of bubbles because bubbles are slowing down the movement of juice. 04. with increase in slope the movement will b faster. 05.hold it at that position and you will b able to transfer your lemon juice in a few seconds. please replay with a remark sir.
You could calculate it... take the tunnel length, multiply by the cross sectional area and divide the volume of lemonade by this. The ratio is numerically equal to the time times a constant. The constant(which we shall call the Lewin Bottle constant) depends on the bottle. Right?
Lectures by Walter Lewin. They will make you ♥ Physics. Interesting...say, what would happen if somehow we managed to attach the thin end of one vortex to the thin end of another, making them coaxial? If they’re spinning in different directions, they cancel out, but if they’re spinning in the same?
very simple just put bottle assembly horizontal and then tilt it slowly (means keeping empty bottle at ground and very gently lifting filled one) .The purpose here is not to have water fully occupying the hole means there must be a maintained passage for air to pass from one bottle to another in direction opposite to fluid flow. ANOTHER WIERED ONE IS TO PLACE THE ENTIRE SETUP ON A SPEAKER .LET IT RESONATE WATER AND BRING IT DOWN DANGER:GLASS BOTTLE MAY SHATTER IF RESONANCE FREQUENCY OF GLASS IS ACHIEVED😎
the answer is you dont turn over the bottles instantaneously you turn it over slowly like you are poring water in a glass so the two bottles would be horizontal and the liquid will pass smoothly the more you tilt the bottles so there would be air above transferred liquid at all time because if you did it your way an air bubble would escape the liquid then it would be replaced with liquid in its place but if you did it the way i mentioned the transfer would be faster because there is not much resistance
basically Proff. we need to increase the rate of air flow in the upper bottle to replace the volume of lemonade. Insert a drinking straw and then join the bottles as shown in the video. ( the ends of the straw must end in different bottles)
I am thinking: Before you screw on the top empty bottle, squeeze it to remove as much air, then overturn the 2 combined and squeeze the top full bottle. That should be the quickest way?
I have yet to try it but here is my solution: Squeeze the lower bottle so the air in it is pushed into the upper one and when it is released the water should fall into it quickly.
we are still friends! :D how about holding the filled bottle horizontally and start rotating so the liquid can rush to the outer side where the empty bottle is, preferably fast to have a centripetal acceleration much greater than "g" to avoid the liquid to stall like happened to you in the demostration
make that bottles horizontal and slowly tilt the system such that the tunnel has enough space to exchange both air and liquid simultaneously without passing thought each other (as they did in vertical case)
If the bottom one starts out cold, and you heat the very top of the top bottle - the first amount shold transfer quickly. I would then heat the air in the bottom one and cool the air in the top one to "over equalize" . Then the first step again to get out the rest. I wonder what would happpen, if the middle connector was a radiator wich was supercooled. The same fluid could excert pressure when in top and suction when in bottom. would be cool.
dear Lewin. i luv all ur physics lectures.i study at a small college in an unknown island known as Sri Lanka. as the lectures are awful in here, i just read physics book and watch ur videos to get them cleared. JUST WANNA SAY THANK YOU. u have transformed my life. I am deadly sure that one day I will refer ur name infront of a great audience.
put baking soda in upper bottle, formation of CO2 will increase pressure in upper bottle= faster lemonade transfer.. Easy :) (depends on concentration of lemon juice)
Just now I got to know that I am not allowed to put holes. If that is the case, then I will tilt the bottle setup such that it makes some acute angle w.r.t ground, ensuring that both air and water has path to move via the opening.
hi sir ........i think if we reserve a small part, of gap(where liquid transfers from one bottle to other or where mouth of bottles are attached) for air flow than liquid may flow easily...for this we can keep both bottles system at some angle from ground...which must be changed by us continuously..
Puncture the lower bottle at the top and the upper bottle at its bottom. Add compressed air in the upper bottle and lower the pressure in the lower bottle to get the fastest flow, the greater the pressure differential the greater the flow.
Wrap the empty bottle with ice pack, and heat bottom bottle with hair drier, thus expanding Air pressure. When bottles are flipped, hot expanded air forcing the liquid to the cooler condensed bottle?
I think we can put the bottom bottle into ice water, because it will cause low pressure that sucks the lemon juice. Am I right? And thank you for all your physics riddles :)
If we are allowed to make a hole in the bottle, then as soon as you turn these bottles, so that it starts dropping the water, I would quickly make some hole at the top, so that the air can come in and this will increase the speed. There is also another, simpler method: simply hold the bottle under some angle, so that the water will go the fastest. But to find this angle you should either do lots of tries or do math calculations.
so i AM just a recent learner but the only way i see to do this is to find an answer on the fluids mechanics (i AM sorry for my spelling mistakes but i AM portugueses 😅). if we can somehow use a pomp of Air, attending to Bernoulli laws and eq, we can acellerate the air in the upper bottel witch is going to reduce presure and the liquid will flow up. i dont know if it works or not but does a vacuum bomb woudl resolve our problem? if so why and why not
i think i have a solution, the air into the bottle is divided in 2 parts and the lemon juice compress the bottom one and expand the other, which makes the pressure from the bottom larger, rotate the bottle for a short while should create kind of a "tunnel", so that the volume of the air will be constant and will not counter the gravity force, in that way the liquid will fall faster please excuse my english i hope you can understand me
you can use vacuum system. use some hot or even boiling water to increase two bottles temperature from outside then rotate bottles slightly from horizontal maybe 45 degree so lemonade wont make the bottle neck on joint then put the empty bottle in cold water so it decrease air pressure in empty bottle and suck lemonade much more faster .so here we decrease the gravity effect but help to avoid bottle neck in the other hand make empty bottle act like a water pump .
Sir, I haven't done anything but I expect them to transfer instantly if two bottles are like cylinerical pipes of uniform diameter connected with each other.
I would make a hole in the bottom of one of the bottles and would attach a straw in this bottle. Then, by blowing air inside it the pressure would increase and the liquid would pass from one bottle to the other quicker.
without having attempted to replicate the experiment, i think that the fastest technique would be to attach a straw in the middle which has its tips on the middle of the bottles...
Challange accepted - right now 3D printing bottle connector, since here in Croatia we have nothing 'handy' at market. Just noticed your video, and I know the answer, but want to proof it. Dear Walter, do you accept video reply?
first squeeze the the upper empty bottle and then invert the system such that squeezed part in lower and let the upper liquid filled bottles pour the liquid into lower squeeze bottle, while doing this squeeze the upper filled bottle
well, here the problem is empty bottle isn't empty at all , definitely it have air . so the to fill the bottle with liquid(lemonade) instantly we must provide a two way (i.e. another way to pass air from empty bottle to lemonade bottle. since we are talking about physics here. i will try to do it practically, if succeed i will send u mine solution. :)
sorry seen the next video puncture is not allowed. So straw can be used so that air flows between the two bottle without any hindrance, already so many replies for it.
sir.. where did u get the connecting tube. or did u make it at home... I wasn't able to get it. So, I taped the bottles together. Please tell me if it's fine if taping the 2 bottles with equal radius of the opening..
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Yeah We are your Beloved Viewer.. Have a nice day sir, We are still friends... rather friendship is getting stronger with more and more lectures.. and Problem of the Weeks...
*:)*
nice video young man...!
thanks for the *young*
Lectures by Walter Lewin. They will make you ♥ Physics. thanks for inspiring me to pursue physics
Sir, the best way is to shake the bottle such that it takes least time to empty :)
Sir u r one heck of an artist, you painted the beauty of physics on the canvas of our minds. Tysm.
Love and Respect.
:)
I am just a normal person with no College education I love doing the different experiments each week i truly hope you keep them up I did this one what I have found is two different ways of doing this in a different way 1 is not to turn the bottles all the way up but keep them at a angle 2 and the most effective way I found is to fill a sink up with hot water them turning it upside down in the hot water the gases over power the surface tension of the water in the bottles my best time was 16 seconds thanks so much
About two weeks ago I finished watching all Yours 8.0x lectures with great pleasure. Thank You for all these lectures and great experiments. I was very good in math and physics during my education, but I learn a lot new things and saw explanation for many things that I knew that exist, but did not know what is really happened.
So, said that, I saw this in one of Yours lectures, so I will not give solution here, it is simple but not so intuitive at first moment.
Best regards from Srbija.
I think the fastest way is to first flip bottles just like you did so gravity will do the work and then constantly shake top bottle in circles because than water will crate spiral and it will fall faster.
I didn't try it yet but i think that it will be about 2 times slower (about 30-45 seconds).
Thanks for still making videos at this age and helping kids and young people learn physics in a fun way with really good professor!
I started with watching your lectures just yesterday and now am so much loving ur lectures that I started watching from ur problem 1 ..read about rattle back now going to make the setup in problem 2. You are that brilliant teacher any student would wish of
Without carry out experiment, I can think of starting with Bottles align parallel to Earth Sufrace, then further rotating for next 90-deg with appropriate speed that liguid Flow does not block.
Dear Dr. Lewin,
Love your style of teaching, it is informative and entertaining at the same time. You are to be commended for all the countless viewers that you have inspired.
In your last video on the subject of the lemonade transfer problem, you made mention of possibly entertaining suggestions for 'interesting' physics problems. While perhaps a bit too esoteric, the two capacitor paradox is one that causes many to scratch their heads trying to explain the results. I have had fun with this one in my engineering circles on many occasions. There are so many different approaches and nearly as many analogs to the paradox that it could spark up some interesting exchanges.
Hey Dr Walter,
Sorry, I have not done the experiment so, I do not have any duration but I have a theory. The "problem" is after the set up, the system is at equilibrium (same pressure, temperature and volume). When you flipped the system and gravity starts pulling on water, the more water goes to the second bottle, the more pressurized it becomes because the volume taken by air is decreasing. The exact opposite happens to the bottle on top. This prevents water from transferring as fast as it can because there is always a force going from high to low pressure.
So, my solution is that before and while water is transferring, the top battle can be heated to increase the pressure (but not as much to melt the bottle) and the bottle below can be placed in ice to low the pressure. Then, the transfer time should be much lower.
wish if our education system has such types of problem drill or test....professor u are amazing, u always make us love physics
by constantly shaking we might transfer lemon juice little faster. i done similar thing before, it took around 1 min. to transfer.... tnx Mr. physics for these kind of puzzles and questions.
I love this channel. It really makes people think about the challenges.
Professor, Honestly i made myself a big fan of yours intelligence.. And i ve downloaded your classical physics and electricity and magnetism and this is what i do.. i will take a note of everything what you say in those lectures as your students do in your class.. And i really really loved physics after seeing your lectures and videos..In fact i have a folder in my computer as Walter Lewin..
Hello Dr Lewin, sorry to have kept you waiting, was preparing for my Skippers Exam in the Netherlands. To cause of this problem is clearly a battle between surface tension, partial vacuum in the top bottle and gravity. When left alone surface tension will Wim and form a stable small surface in the part that connects both bottles. as I cannot enter a soap, I must return to physics. So I need to enter another factor to destabilise the surface. I guess swirling will be effective. It prevents a surface building up.
Does remind me of my student days back in '77. My graduation project in chemical engineering dealt with the Marangoni effect. Example: evaporating alcohol from liquor will cause drops to build on the glass which creep up before falling down in the rest of the fluid.
Keep up the good work. I enjoy these very much, groeten uit Leeuwarden, NL
Hoe ging je examen?
Lectures by Walter Lewin. They will make you ♥ Physics. Geslaagd, ik mag nu groepen vervoeren...
Hello, I think the best way to do it is to squeeze the upper bottle, hence pressurizing the lower one and taking some liquid with it. After some time you have to squeeze the lower bottle to force some air to the upper bottle. Then you start from the beginning. The exact time depends on how handy a person is and what kind of bottle that is, but it can be done in a few seconds only.
I love that you're retired now and THIS is how you choose to entertain the internet world
I haven't made the dual-bottle thing, but I'll use yours. That is, in my head. I start with compressing the top bottle so that most of the air will be in the half-filled bottle. When I now turn the whole thing upside down, the fluid will *rocket* down, and I guess it will take around five seconds.
I got it
First we will reverse the bottle where the filled bottle will be on top and empty bottle at the bottom...
Then we will squeeze the empty bottle and leave it ...The water will start filling faster due to pressure....and repeat the process until the bottle at the top is empty.... honestly I assumed it by my own.....becz I noticed it when I used to fill bottle in my childhood and to complete my work faster I discovered this technique....
I just connected two bottles and sealed them with seal tape, I taped a straw to the inside of the bottles' necks, one end of the straw goes deep in the bottle containing the water and the other end of the straw is at the top of the bottle being filled and it took me just less than 4 seconds to transfer one liter of water.
Just pass a straw between two bottle necks such that one end of the straw is in the empty bottle and near to the neck and other end of straw to the deep inside the filled bottle so that when the bottle gets tilted upside down both ends of the straw will be in air. As a result of that air will pass through straw smoothly and lemonade will pass through the bottle joint.
Sorry I will not be able to make a model to get the answer practically, but I can do it theoretically by knowing some values like lemonade density, straw diameter, bottle neck diameter etc.
You are an artist sir, I get a lot of help in physics from your videos.
Abhishek Rodwal put a hole in center of straw, thus drawing air from outside of the bottle.
Abhishek Rodwal do this to both bottles about the fill area?
Sir I intended to pass that straw from inside of the two bottles, maintaining the isolated system, so that air pass from one bottle to other.
And are you suggesting to take air from outside, because that's against the rule. Another video of Walter sir indicated that rule to not to punch a hole in bottle.
Or I failed to get your concept???
Abhishek Rodwal yes you correct. Thank you
Thank You
So, I built this thing. I cut open 2 caps, put one bottle with 1 liter water in the freezer. put the other bottle in the oven at 50 C only. After one hour ( water cold but not frozen ) i taped upper and lower bottle together ( with cut open caps on to give the tape some surface ) and turned it over. Transfer was done in about 6 seconds. So I thought i figured it out. Then i turned it over the next day, all at room temperature .... transfer took about 7 seconds.
Apparently, in my case, temperatures do not matter much.
Then i spotted a difference with prof. Lewins video. My water comes down on the plastic inner surface of the lower bottle , wo exception, in a more or less smooth way unlike Prof. Lewins video.
My conclusion it that the surface roughness inside of the connection between the bottles makes all the difference. If it is rough it will soak up and attract the water, which makes it pass on the outside. The air in turn will take the center to flow. This way the two flows are not opposing each other and upper and lower surface pressure will not stabilize equal, causing it to not stop and flow fast.
cutting was NOT allowed. View my 2nd video on the subject
Sorry, but i don't think you understand correctly. The caps are just part of the tunnel and airtight to the outside. I just made a round hole in the top and they are only there to have a good surface for the tape. I could just have taped the threads together, i think with simular results.
However, I sense my answer is not the one your looking for. I'm eager to hear you explanation
My tunnel is also shorter than yours.
I hope the problems keep coming :-) These are fun. I understand how hard it is though to come up with something original
At a point, the weight of the water+some air above it in top bottle is equal to the pressure of the air in the bottom bottle. This air in the bottom bottle has to be displaced by the water from top bottle. Put a small hole at the top of the bottom bottle so that the air from the bottom bottle escapes out and water takes its place.
You're a very entertaining teacher, I was sad when I realised I didn't have enough understanding to make use of your lectures. This problem looks to much like the Jerry can problem. A smaller hole was added to the back of a jerry can to stop the gurgling, hole was a lot smaller than the pour hole as the difference in density. I would start with making the tunnel as clear as possible and have a straw sticking 6 inches into either bottle for the air passage. The fact that your fluid stopped makes me think you have some trickery in your tunnel
I am sorry that I am posting this comment before doing the experiment but I feel that along with gravity, we must also allow pressure to do the work, as it is a closed system. So, my idea is to just press the bottle on the bottom when the system is made upside down.
I feel that this may take well below 10 seconds, if done with proper practise and good technique.
Squeeze and release. the bottom bottle. Is that allowed? The restriction is caused by the constant increase in pressure in the lower bottle and the decrease of pressure in the upper bottle as the liquid transfers. This eventually causes the air to be forced up to the upper bottle. A little squeeze of the lower bottle forces the air up, and "above" the liquid, increasing the pressure in the upper bottle, then the release of the lower one, lowers the pressure in that one and the liquid is forced under pressure into the lower bottle. It's basic pressure/ flow rate physics. The same process can be applied to electrons stored in a capacitor.
Turn the bottle upside down and the one with lemonade should be squeezed because of which pressure is built and takes almost up to 10 to 15 seconds for the lemonade to gush out
it will be even better if the bottle without the lemonade is squeezed before transfer
warmup the empty container. this would cause the air to expand. then get the bottles connected. when the empty bottle cools down a vacuum exist in it. invert the system. this method will ease the flow since high pressure would exist on the lemonade when inverted. this would increase the velocity of flow. thereby decreasing the time.
I have at least three options:
the first one is to put this construction horizontally to produce a free transfer of liquid and air inside;
the second one is to do the same thing like it's shown in this video but with squeezing a bottle on top to produce greater acceleration of the liquid inside;
the third option is to just shake the whole construction.
All my other options are just some combinations of these three opportunities. I guess I'll try them tomorrow.
none of your 3 options are "winners"
Thank you. I guess it's time to think a bit more.))
But what if I give some extra acceleration by just moving this construction up supper fast? Not just shaking it up and down (I used the wrong word when I described the third option). I guess it may give an extra acceleration which depends only on how fast I can do it. If I do it supper fast can this option become the winner?
i think by broaden the tuneel between the two bottles and making another way of conection between the two bottles so the air transefer when the liquid takes place
Sir, there are two solutions, 1.Make a hole in both bottles where there is air , the water will move quickly because the air resisting its flow will out from the hole in lower bottle due to increasing pressure and move inward in the upperbottle where pressure is decreasing.
2. make the bottle horizontal so that the space in the tunnel is somewhat occupied by the lemonade and rest empty ,and then slowly tilt it so that there is always space for air to travel from one bottle to other.
hii i m swadhin .
thnx for your lectures sir. i m a great fan of your.
let me solve this first.......
sir u have to do just following things:
01.make the bottle-system horizontal with the force of gravity.
02. now slowly tilt it towards the empty one.
03.then your favorite lemon juice will start going towards empty one.
03.increase the slope of the bottle-system slowly and try to avoid formation of bubbles because bubbles are slowing down the movement of juice.
04. with increase in slope the movement will b faster.
05.hold it at that position and you will b able to transfer your lemon juice in a few seconds.
please replay with a remark sir.
I have watched your lectures and I fortunately also watched the one in which you did the same experiment.
TADA
Maybe you should squeeze the bottom one, compression of the air forces it to find it's way through lemonade faster.
You could calculate it... take the tunnel length, multiply by the cross sectional area and divide the volume of lemonade by this. The ratio is numerically equal to the time times a constant. The constant(which we shall call the Lewin Bottle constant) depends on the bottle. Right?
en.wikipedia.org/wiki/Vortex
Lectures by Walter Lewin. They will make you ♥ Physics. Interesting...say, what would happen if somehow we managed to attach the thin end of one vortex to the thin end of another, making them coaxial? If they’re spinning in different directions, they cancel out, but if they’re spinning in the same?
very simple just put bottle assembly horizontal and then tilt it slowly (means keeping empty bottle at ground and very gently lifting filled one) .The purpose here is not to have water fully occupying the hole means there must be a maintained passage for air to pass from one bottle to another in direction opposite to fluid flow.
ANOTHER WIERED ONE IS TO PLACE THE ENTIRE SETUP ON A SPEAKER .LET IT RESONATE WATER AND BRING IT DOWN
DANGER:GLASS BOTTLE MAY SHATTER IF RESONANCE FREQUENCY OF GLASS IS ACHIEVED😎
Many thanks for yours lectures professor they are all amazing. And thank you for inspire me to study physics. Warm regards from Argentina
the answer is you dont turn over the bottles instantaneously you turn it over slowly like you are poring water in a glass so the two bottles would be horizontal and the liquid will pass smoothly the more you tilt the bottles so there would be air above transferred liquid at all time because if you did it your way an air bubble would escape the liquid then it would be replaced with liquid in its place but if you did it the way i mentioned the transfer would be faster because there is not much resistance
I'm loving every single one of these videos sir
You are the man 👌
basically Proff. we need to increase the rate of air flow in the upper bottle to replace the volume of lemonade. Insert a drinking straw and then join the bottles as shown in the video. ( the ends of the straw must end in different bottles)
I am thinking: Before you screw on the top empty bottle, squeeze it to remove as much air, then overturn the 2 combined and squeeze the top full bottle. That should be the quickest way?
I have yet to try it but here is my solution:
Squeeze the lower bottle so the air in it is pushed into the upper one and when it is released the water should fall into it quickly.
we are still friends! :D
how about holding the filled bottle horizontally and start rotating so the liquid can rush to the outer side where the empty bottle is, preferably fast to have a centripetal acceleration much greater than "g" to avoid the liquid to stall like happened to you in the demostration
make that bottles horizontal and slowly tilt the system such that the tunnel has enough space to exchange both air and liquid simultaneously without passing thought each other (as they did in vertical case)
Tilt the bottle so as to allow easy exchange of air. Use only half the opening for the flow of liquid.
If the bottom one starts out cold, and you heat the very top of the top bottle - the first amount shold transfer quickly.
I would then heat the air in the bottom one and cool the air in the top one to "over equalize" .
Then the first step again to get out the rest.
I wonder what would happpen, if the middle connector was a radiator wich was supercooled.
The same fluid could excert pressure when in top and suction when in bottom. would be cool.
Are we allowed to create pressure differences inside the bottle by way of heating and cooling?
A also interested in why did the water stopped dripping :-) 03:00
dear Lewin. i luv all ur physics lectures.i study at a small college in an unknown island known as Sri Lanka. as the lectures are awful in here, i just read physics book and watch ur videos to get them cleared. JUST WANNA SAY THANK YOU. u have transformed my life. I am deadly sure that one day I will refer ur name infront of a great audience.
:)
is this really lewin replying?
I Walter Lewin) run this channel. I make all the new "Live" videos. I answer questions and occasionally I write :). have a nice day
It slowed down because the differential in air pressure in the bottles maybe?
put baking soda in upper bottle, formation of CO2 will increase pressure in upper bottle= faster lemonade transfer.. Easy :)
(depends on concentration of lemon juice)
Just now I got to know that I am not allowed to put holes. If that is the case, then I will tilt the bottle setup such that it makes some acute angle w.r.t ground, ensuring that both air and water has path to move via the opening.
hi sir ........i think if we reserve a small part, of gap(where liquid transfers from one bottle to other or where mouth of bottles are attached) for air flow than liquid may flow easily...for this we can keep both bottles system at some angle from ground...which must be changed by us continuously..
Puncture the lower bottle at the top and the upper bottle at its bottom. Add compressed air in the upper bottle and lower the pressure in the lower bottle to get the fastest flow, the greater the pressure differential the greater the flow.
We can free up some of the air inside the empty bottle but I didn't test it still.By the way, thanks for this new -series- of physics problem!
test it
Always leave some place for the air at the connector so the pressure can compensate without lifting up this heavy ass lemon juice :)
Wrap the empty bottle with ice pack, and heat bottom bottle with hair drier, thus expanding Air pressure. When bottles are flipped, hot expanded air forcing the liquid to the cooler condensed bottle?
Hello! My name is Hassan. I have a small request, can you make a detailed video on relative velocity it would be very helpful.
In my "solution" video of course I will demonstrate the best solution.
I think we can put the bottom bottle into ice water, because it will cause low pressure that sucks the lemon juice. Am I right? And thank you for all your physics riddles :)
This is pretty much the same you see in the water cans and say you have a diffuser in between
Add a straw in between the lid to stable the pressure in both bottle
If we are allowed to make a hole in the bottle, then as soon as you turn these bottles, so that it starts dropping the water, I would quickly make some hole at the top, so that the air can come in and this will increase the speed.
There is also another, simpler method: simply hold the bottle under some angle, so that the water will go the fastest. But to find this angle you should either do lots of tries or do math calculations.
so i AM just a recent learner but the only way i see to do this is to find an answer on the fluids mechanics (i AM sorry for my spelling mistakes but i AM portugueses 😅). if we can somehow use a pomp of Air, attending to Bernoulli laws and eq, we can acellerate the air in the upper bottel witch is going to reduce presure and the liquid will flow up. i dont know if it works or not but does a vacuum bomb woudl resolve our problem? if so why and why not
i think i have a solution, the air into the bottle is divided in 2 parts and the lemon juice compress the bottom one and expand the other, which makes the pressure from the bottom larger, rotate the bottle for a short while should create kind of a "tunnel", so that the volume of the air will be constant and will not counter the gravity force, in that way the liquid will fall faster
please excuse my english i hope you can understand me
you can use vacuum system. use some hot or even boiling water to increase two bottles temperature from outside then rotate bottles slightly from horizontal maybe 45 degree so lemonade wont make the bottle neck on joint then put the empty bottle in cold water so it decrease air pressure in empty bottle and suck lemonade much more faster .so here we decrease the gravity effect but help to avoid bottle neck in the other hand make empty bottle act like a water pump .
even you can use boiling water(lemonade :D) inside the bottles and switch between them to two bottles almost get boiling water temperature.
try it
Does the clock start ticking when the first drop enters the empty bottle? Or do we have to time any "(kinematic) preparation"?
Turn it on the side and tilt it slowly?
if i change the liquid to boiling water or liquid nitrogen will the same phenomenon can be seen?
Sir, I haven't done anything but I expect them to transfer instantly if two bottles are like cylinerical pipes of uniform diameter connected with each other.
I would make a hole in the bottom of one of the bottles and would attach a straw in this bottle. Then, by blowing air inside it the pressure would increase and the liquid would pass from one bottle to the other quicker.
Why did the water stopped? And should I post my solution in the comments?
Adding a long straw inside both the bottles should make it faster!
Using thumb pin pierce a hole at the neck of the lower bottle and another hole at the base of the upper bottle. :)
without having attempted to replicate the experiment, i think that the fastest technique would be to attach a straw in the middle which has its tips on the middle of the bottles...
place the two bottles horizontally and raise the bottle containing liquid slowly and transfer the liquid into the empty one
i can do faster then that...
then share you're findings!
Nice
Challange accepted - right now 3D printing bottle connector, since here in Croatia we have nothing 'handy' at market. Just noticed your video, and I know the answer, but want to proof it. Dear Walter, do you accept video reply?
first squeeze the the upper empty bottle and then invert the system such that squeezed part in lower and let the upper liquid filled bottles pour the liquid into lower squeeze bottle, while doing this squeeze the upper filled bottle
I love your physics problems and videos, sir!
Drill holes on the neck of the lower bottle this will allow the air to escape.
not allowed
why did the transfer of lemonade come to a hault in the middle ??
well, here the problem is empty bottle isn't empty at all , definitely it have air . so the to fill the bottle with liquid(lemonade) instantly we must provide a two way (i.e. another way to pass air from empty bottle to lemonade bottle.
since we are talking about physics here. i will try to do it practically, if succeed i will send u mine solution. :)
puncture the top bottle at the top, so that vacuum is not created in the top bottle which stops it from flowing downwards
sorry seen the next video puncture is not allowed. So straw can be used so that air flows between the two bottle without any hindrance, already so many replies for it.
Do u have any specific lectures dealing with magnetism and quantum mechanics?
yes
see my 8.01 and 8.02 lectures on this channel
usuario is It allowed to add some thing in the tunnel?
sir my answer is that I was thinking if we connect an narrow connecting tube in between the two bottles
could you specify better what am I allowed to do/use and what I'm not allowed?
The lemonade will fall faster if bore a hole in the bottle which is present at the top containing it :)
Isn't this the same demonstration from one of your lectures in 8.03?
I just watched a 6 minute video about lemonade dropping out of a bottle...
Hello professor my physics teacher suggested to look your videos and I love it :)
:)
if we swirl the liquid initially then it will go down fastest
Your pulling the upside vacuum by letting the water drip to the other bottle.
sir can we do it with 1 litre bottles and fill one of them 500 ml ? I can't find such 2 litre bottles.
its awsome u are making me love physics
Anybody know what the thread pitch for those bottles are?
sir.. where did u get the connecting tube. or did u make it at home... I wasn't able to get it. So, I taped the bottles together. Please tell me if it's fine if taping the 2 bottles with equal radius of the opening..
that's fine
Where can I buy the tunnel bottle closure?
it's much easier to tape them together so that the openings face each other.
press the bottle which contains the liquid. . air will compress liquid won't. . it will escape to the other bottle. . flip them over and that's it.
Ali Alshekarchee I think that doing that you can also locked up some liquid in the first bottle.
not if you're doing right .. flip them like in the video and just squeeze the top part of the bottle.
walter you are the best teahcer in the whole world love from india