8.01x - Module 17.02 - Unusual characteristics of the center of mass

Unusual characteristics of the center of mass

[@stabmaa]

Presentation with politeness and humbleness make your lecture great . You voice modulation and body language make bonding with viewer very strong. 👌👌👌👌👌👌

[@lecturesbywalterlewin.they9259]

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Playing with object and an understanding the concept of physics is farfar better than play with the physical quantities and get good marks in exam without any concept

[@satyamjha18]

I do not know how to thank you in words sir♥️ I was so confused with this thing But you made it clear as a crystal Thank you so much sir. I must say, You are a Legend sir♥️♥️

[@Sambhaji_Jadhav_984]

This video is 5 years old but without a single dislike

[@narek323]

I wish I had a professor that is as concise and clear as professor Lewin.

[@pranjalyadav7917]

This guy is amazing

[@lecturesbywalterlewin.they9259]

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[@ShubhamParikh]

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[@lecturesbywalterlewin.they9259]

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[@ShubhamParikh]

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[@dragosstrugar3097]

I wish every professor had the enthusiasm and the love for his/her field of research and interest as you do. Thank you for your contributions to science, and for inspiring millions around the globe to pursue a career in science.

[@lecturesbywalterlewin.they9259]

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[@harshraj3255]

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[@lecturesbywalterlewin.they9259]

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[@sonalvora4954]

Lectures by Walter Lewin. They will make you ♥ Physics. That's swag ! My son Loves you sir!

[@AnthonyFrancisJones]

Could someone kindly explain when it is correct to use the term "centre of gravity"? I appreciate that this should be at the centre of mass but keen to get the usage correct.

[@porte_bosho]

Did u get ur ans?

[@carultch]

In our every day experience, center of mass and center of gravity are close enough to each other, that the terms can be used interchangeably. This is something we take for granted when our example takes place in a uniform gravitational field. When we do NOT have a uniform gravitational field, there is a difference between center of mass and center of gravity. Center of mass ignores gravity, and just looks at sum(xi*mi)/sum(mi). Center of gravity inserts a g in to each mi term, such that you get sum(xi*mi*gi)/sum(mi*gi). Consider an example, where you have a 1000 km rod of negligible mass, connecting two bodies of negligible dimensional size, whose masses are 1000 kg and 2000 kg. The larger mass is sitting on the surface of Earth, and the smaller mass extends vertically in to space. Take M=5.98e24 kg and R = 6.371e6 m as the mass and radius of spherical Earth. Calculate A) the center of mass of this pair of masses, and B) the center of gravity of this pair of masses. Answer: A) center of mass = 333 km above Earth's surface, and B) center of gravity= 270 km above Earth's surface.

[@abhimankher8594]

Why is the center of mass defined the way it is. What gives it the special property of being accelerated by the magnitude of (net force applied on the body)/(mass of body) in the direction of net applied force , whereas the "ordinary" particle of rigid body may have a different acceleration of its own?

[@carultch]

If you apply a force to the center of mass, or a collection of forces with moments with moments (aka torques) about the center of mass that add up to zero, the object will have purely linear acceleration. If you apply the force elsewhere, you will have rotational acceleration in addition to linear acceleration. Applying a force elsewhere than the center of mass will apply a torque to the object that causes rotation. The center of mass is a point at which we can approximate the object to behave as if all mass were concentrated at that point, when applying the linear version of Newton's laws.

[@kishankarkee2156]

which book page 5.7 did you refer here in this video?will you mind telling me?

[@lecturesbywalterlewin.they9259]

prabably Ohanian

[@ved4590]

There may be science behind that cotton Bracelet!!!!!!!!!!!!

[@niamaaqarial529]

where can I find the book that he mentioned?

[@JaiPrakash-bk3uv]

sir if there is torque acts on body than it is necessary there is angular frequency on it. is am I dight

[@lecturesbywalterlewin.they9259]

no not correct if w = 0 I can apply a torque w will then change.

[@arunteltia7888]

wow

[@subhabrataghosh3565]

do you have any lecture on center of gravity? sir.

[@lecturesbywalterlewin.they9259]

:)

[@subhabrataghosh3565]

do you have any lecture on center of gravity? sir.

[@aryanshshrivastava2650]

@@subhabrataghosh3565 Center of gravity and mass are the same thing

[@carultch]

@@aryanshshrivastava2650 Not necessarily. In a simple example with uniform gravity, they are the same point, but they are not defined identically. Center of mass is independent of any gravitational field. Center of gravity will be different if the gravitational field is non-uniform enough that variation must be considered. Center of gravity is the point about which the net torque due to gravity diminishes to zero. Center of mass is the center of a distribution of mass in space. A "weighted average" of the position of each particle that makes up the system, based on mass.

[@kaminipandey3595]

Sir please tell which book's page are you referring?

[@lecturesbywalterlewin.they9259]

8.01 Physics Hans C. Ohanian Physics Volume 1 2nd edition W.W. Norton & Company ISBN 0-393-95748-9

[@kaminipandey3595]

@@lecturesbywalterlewin.they9259 Thank you sir

[@kaminipandey3595]

@@lecturesbywalterlewin.they9259 Sir, how does the magnitude electrical current remains constant in a wire(formation of surface charge on the wire) ? And sir can poynting vector explains that how exactly energy flows in a battery resistant Circuit? Please explain it by making a video on it🙏🙏

[@lecturesbywalterlewin.they9259]

@@kaminipandey3595 I cover all this in my 8.02 lectures. Plse watch them

[@kaminipandey3595]

@@lecturesbywalterlewin.they9259 Sir I have a question and have to insert an image for that but unable to attach it as it is the comment box.How can I ask you?

[@user-ez6kn6pc8z]

which book you are referring here

[@lecturesbywalterlewin.they9259]

question unclear. "here" is ill-defined

[@abhisht_indulkar]

[@saniyazahid5282]

Sir, Is the centre of mass only at one point reply please

[@lecturesbywalterlewin.they9259]

www.khanacademy.org/science/physics/linear-momentum/center-of-mass/a/what-is-center-of-mass

[@JaiPrakash-bk3uv]

sir is centre of mass depend upon our origin

[@lecturesbywalterlewin.they9259]

use my lectures or google

[@JaiPrakash-bk3uv]

what is definition of centre of mass

[@lecturesbywalterlewin.they9259]

use my lectures or google