Energy Problems - Review Session

Physics Ninja solves 16 problems - 46 questions relating to the work-energy theorem and conservation of energy.
Download the problem set:

[snapls]

The fact this was uploaded exactly a week before my test on this is crazy

[jacksonr]

Following along with the printed out problems, trying them first, then watching the video to see what mistakes you might have made is THE BEST studying for physics. The BEST. Thank you sir.

[MaxRypert]

After failing physics multiple times, I just got the results back from my Physics retake exam and I got a 9.3/10! Your videos have been incredibly helpful. So truly, many thanks for doing what you do!

[huynh]

Love your videos, I bought your courses and they’ve been helping me a lot

[seekingmetallurgy]

fruitful explanation on this subject~ will help a lot during my midterm. thank you!

[Keira-dcwv]

1. For problem 3, why can those two areas cancel out each other when work is a scalar quantity?
2. Problem 6, since force that's being applied to the sled is provided, why can't you just multiply that to the distance traveled? And if there's a force being applied, the velocity is not constant throughout A to B, why are we using the Kinetic energy?

[darkrising]

Sir can you please do linear momentum, collisions, and impulse problems next?

[nickvlahos]

The energetic delivery renews my drive to learn! Cool!

[farragoprismproductions]

_The timing could have never been any perfect..._

[MohamedKeita-qcbk]

hello Sir in problem 8, isn't the work equal to the force multiplied by the distance so why did you take the variation of the kinetic energy instead of multiplying the force by the distance...

[victoryfirst]

Hi! I have a request for you. Could you make a video about the following problem? I don't know how to do it with either the Lagrangian or Newtonian mechanics, and I've not seen a solution to this problem online.

A disk with mass M and radius R is rolling down an inclined plane that makes an angle θ with the horizontal, without slipping. A block with mass m is attached to the disk via a massless rope and a massless/frictionless pulley in such a way, that the rope will wrap around the disk when the disk rolls down the incline, and the mass will move up (i.e. it is initially attached tangentially to the top of the disk).

What is the acceleration of the block?

I know the key to this problem is that the block will have an additional acceleration because the rope wraps around the disk, having an extra α*R term for acceleration. But no mention has been made of the constant rolling friction force, and I don't know how to solve the problem without this. The friction force should be the force that gives the disk a net torque in the clockwise direction (that is down the slope). Also, I don't how to incorporate the wrapping around the disk into the equations for the Lagrangiang (I do if the rope was attached to the center of the disk).

P.S. You're channel is one of the best physics channels ever! Keep up the great work!

[sofyakrasikova]

Doesn't kinetic friction take away from work done by kinetic energy not gravitational potential energy?

[avaryhills]

shouldn’t work done by gravity be negative for Problem 11 question 20? Why did you say it was positive?

[AnanyaGupta-ywyf]

Hi, would you be posting more review sessions with the topics for the upcoming ap physics 1 exam? Your videos have helped in studying.

[abhijeetgaming]

Sir from which book I should study physics for advanced

[MohaleNdlovu]

sir how did you get 115 degree in problem 10

[hayaalkar]

Hi can you please make video to review physical 2 for the book serway from chapter 23 to 30 ?