Great video, keep like that, but i want to know why at 2:45 mark, in τ= I α you make T2 positive and T2 negative ; my doubt is in torqs that counterclock wise is (+) and clockwise is (-) great video :)
In engineering courses, we carefully define a system around each component: the upper block, the pulley, the lower block, and do a force balance on each. We were properly drilled in defining systems in our chemical engineering courses (I was a chem eng major, not mechanical, but the same principles apply). Not saying you did anything wrong here, Professor Biezen, or that you had to do it the way I suggested for a problem of this simplicity (which is still pretty complex: I am sure I would have gotten the wrong answer had I attempted this on my own, since it has been a long time, since high school physics and one year of college physics).
This lesson reminds me of years in high school. By the time, I really fell in love with physics, especially the part of Newton's laws, motion of solids, and laws of conservation of energy. It felt so good when I could use these laws to work out the acceleration or velocity and then imagine how all the blocks move.
Wait, something's off. How do the two tensions cause different torques? Isn't T1 also causing a clockwise torque, since it's moving along the direction of motion?
Draw a free body diagram around the pulley. Relative to the pulley, T1 pulls to the left and T2 pulls down. The draw a free body diagram around m1. Relative to m1, T1 pulls to the right.
Two blocks with masses M1= 5 kg and M2= 15 kg are connected by a rope as shown. the horizontal surface has no friction and the pulley is weightless. If the block starts from rest , What is the speed of M2 if it has fallen 6 meters.
If the mass wasn't given, then perhaps the moment of inertial was given. If neither was given then perhaps the problem did not intend for you to use the moment of inertia. (Sometime they state a LIGHT pulley, or massless pulley). Then use F = ma techniques shown in our videos in chapter 4 and 5.
We have several playlists showing how to do that in the physics playlists. Let me know if you can't find them. We are also working on these summary videos on the energy conservation type problems.
Are you concerned about the negative sign? Note that the object on the table is accelerating to the right (+) and the object hanging is accelerating downward (-). Or you can express the acceleration of the system with an arrow and then express the magnitude (2.8) which is always positive.
That is an interesting question. Usually I am between 0 and 100 % sure the problem is correct. For an older video like this if there is a mistake the viewers probably would have found it.
@@MichelvanBiezen Sir, let me rephrase my question : How to asseverate that the steps adopted for caculation is right? do we have alternate method to cross check the value - final acceleration is 2/7 th of g??? ( Your videos are so lively and elucidate my doubts of 40 years engineering studies now)👍👍👍
400 watt three phase 60 hz motor at 25 rpm I want it to pull a load capacity of 400kgf.m How many N.M does this motor need to do this task? Drum half diameter 12.5 cm
I'm always surprised when I see that T1 does NOT equal T2. I know the physics and math bear that out, but still.. if the string is a continuous piece.. and the tensions are not equal.. then wouldn't the string STRETCH? or Break?.. what if it's a metal cable?.. it seems so counter intuitive.. and yet.. the Math bears it out... .. HA!.. GO FIGURE!! ..
You do actually bring up a good point, which is that this problem assumes a rope which doesn't stretch (massless rope). But even if it did stretch and wasn't massless, we could still have unequal tensions. Tension is more of a "pull" force than a "stretch" force, it that helps.
Great lectures Prof van Bizen.Really simplifies things. We coild improve on the visuals though.its a real pain to see your board. Maybe a blackboard and chalk.No shining and the contrast is much better.
first time I've heard someone speak in your class, I always taught you were alone !
We are actually not in a class, but in our house. Either my wife who films all the videos, or one of our kids my say something during the taping.
@@MichelvanBiezen thought so too
Best physics teacher online, for real!
Just wanted to let you know that your videos are REALLY helpful. Thanks lots
You are the best you talk about all the concepts in each topic ..I always run to watch your videos after learning 😩
Thank you. Glad you found our videos! 🙂
these are everything i need from my lectures in physics, thank you so much
Glad you found our videos. Yes, just about every topic in physics is covered on this channel. 🙂
Great video, keep like that, but i want to know why at 2:45 mark, in τ= I α you make T2 positive and T2 negative ; my doubt is in torqs that counterclock wise is (+) and clockwise is (-)
great video :)
With this technique we call the torque that aids the acceleration positive and the torque that opposes the acceleration negative.
In engineering courses, we carefully define a system around each component: the upper block, the pulley, the lower block, and do a force balance on each. We were properly drilled in defining systems in our chemical engineering courses (I was a chem eng major, not mechanical, but the same principles apply). Not saying you did anything wrong here, Professor Biezen, or that you had to do it the way I suggested for a problem of this simplicity (which is still pretty complex: I am sure I would have gotten the wrong answer had I attempted this on my own, since it has been a long time, since high school physics and one year of college physics).
+The Ultimate Reductionist
I think you are referring to free body diagrams. There are some videos on that topic as well.
I believe that the tensile force from T1 will have no effect on the net torque. Meaning net torque is =RT2.
It turns out that both T1 and T2 apply a torque on the pulley.
Thank you for your posting. It was really heplfull to understand ths moment of inertia
You're a lifesaver, great video!
Thank you bro you came in clutch for my finals
Good luck on your finals.
Thank you for helping me help my little sis with her physics homework
At 3:49 you write m2g - T2, I thought it would be reversed(T2-m2g) since force is a vector and mg is down, T is up.
The method shown in the video uses the concept: Net torque = torques aiding the acceleration - torques opposing the acceleration.
forces aiding and forces opposing-thanks again
This lesson reminds me of years in high school. By the time, I really fell in love with physics, especially the part of Newton's laws, motion of solids, and laws of conservation of energy. It felt so good when I could use these laws to work out the acceleration or velocity and then imagine how all the blocks move.
Thanks, Professor. Very clear explanation.
Glad it was helpful!
hi Michel, your videos are great, do you have any videos explaining inertia and moment of inertia.
thanks in advance.
They are in this playlist: PHYSICS 12 MOMENT OF INERTIA
ty very much, professor ! :D
You are welcome. Glad you enjoyed it. 🙂
How do you know that T1 would cause torque to go in a counter-clockwise direction and that T2 would cause torque to go in a clockwise direction?
Relative to the pulley, T1 pulls to the left and relative to the pulley, T2 pulls downward.
Thank you so much. This was such a short but to the point video.
Glad it was helpful!
Great great question . Bravo
for what it's worth... T2 > T1 .. T2 = (10/7)g T1 = (8/7)g and that is how the world works.. :D
Good way of looking at it. 🙂
Love your lectures sir its truly help me alot 🥰❣️
Great! Glad you found our videos! 🙂
Is there any video explaining how you would do this problem with energy considerations?
Take a look at this playlist: PHYSICS 8 WORK, ENERGY, AND POWER ruclips.net/p/PLX2gX-ftPVXWtv0wrHIHTCUrZHUkVDJiZ
Thank-you!
Wait, something's off. How do the two tensions cause different torques? Isn't T1 also causing a clockwise torque, since it's moving along the direction of motion?
Draw a free body diagram around the pulley. Relative to the pulley, T1 pulls to the left and T2 pulls down. The draw a free body diagram around m1. Relative to m1, T1 pulls to the right.
thank you for posting.
Thank you so much sir 🙏🙏🙏🙏🙏
Most welcome
Two blocks with masses M1= 5 kg and M2= 15 kg are connected by a rope as shown. the horizontal surface has no friction and the pulley is weightless. If the block starts from rest , What is the speed of M2 if it has fallen 6 meters.
can someone answer this please? thank you 😊
This is amazing!!! thank you
Does It still need to multiply to 9.8 right?
Yes, if you want the answer in m/sec^2. The answers are expressed as a fraction of g which is a common way of expressing the acceleration.
How would I go about this same problem if the mass of the pulley is not given?
If the mass wasn't given, then perhaps the moment of inertial was given. If neither was given then perhaps the problem did not intend for you to use the moment of inertia. (Sometime they state a LIGHT pulley, or massless pulley). Then use F = ma techniques shown in our videos in chapter 4 and 5.
Then it is easier because the tension is the same
Why is it T2R-T1R for net torque and not the other way around?
Net torque = torque aiding the acceleration - torque opposing acceleration
@@MichelvanBiezen Thank you!
What a guy! Thanks so much!
Super Helpful!
how can we solve this by energy conservation?
We have several playlists showing how to do that in the physics playlists. Let me know if you can't find them. We are also working on these summary videos on the energy conservation type problems.
@@MichelvanBiezen thank you
understandable thanks
You're welcome
thanks sir
Most welcome
Why T2-T1 but not plus ??
T2 aids the acceleration T1 opposes the acceleration
So good
Thank you. Glad you liked it. 🙂
Thanks for sharing! :)
Glad it was helpful 🙂
Thanks for the video!
You're welcome!
Can he be at my University!
Life saver
Glad the videos are helping.
i solved myself first and then i watch you solved the problem and i got -2.8 is that wrong since i include the mass 1 and gravity?
Are you concerned about the negative sign? Note that the object on the table is accelerating to the right (+) and the object hanging is accelerating downward (-). Or you can express the acceleration of the system with an arrow and then express the magnitude (2.8) which is always positive.
How sure that your calculation is correct?
That is an interesting question. Usually I am between 0 and 100 % sure the problem is correct. For an older video like this if there is a mistake the viewers probably would have found it.
@@MichelvanBiezen Sir, let me rephrase my question :
How to asseverate that the steps adopted for caculation is right?
do we have alternate method to cross check the value - final acceleration is 2/7 th of g???
( Your videos are so lively and elucidate my doubts of 40 years engineering studies now)👍👍👍
Tysm sir💕
400 watt three phase 60 hz motor
at 25 rpm
I want it to pull a load capacity of
400kgf.m
How many N.M does this motor need to do this task?
Drum half diameter 12.5 cm
Top G
Thank you. Glad you liked it.
I'm always surprised when I see that T1 does NOT equal T2. I know the physics and math bear that out, but still.. if the string is a continuous piece.. and the tensions are not equal.. then wouldn't the string STRETCH? or Break?.. what if it's a metal cable?.. it seems so counter intuitive.. and yet.. the Math bears it out... .. HA!.. GO FIGURE!! ..
You do actually bring up a good point, which is that this problem assumes a rope which doesn't stretch (massless rope). But even if it did stretch and wasn't massless, we could still have unequal tensions. Tension is more of a "pull" force than a "stretch" force, it that helps.
Thank you :)
Great lectures Prof van Bizen.Really simplifies things. We coild improve on the visuals though.its a real pain to see your board. Maybe a blackboard and chalk.No shining and the contrast is much better.
Acceleration 2/6 g
There's a mistake
The video is correct. Thanks for checking.
what dafuq is that beeping sound
i love you
Thank you. Glad you like our videos.
michel buy new mic plzzzz
Sounded great here. Must be something on your side.