How to find radius and velocity for angular momentum problems such as collisions or rotating objects that change shape. These are common examples in physics.
one thing i did not get in the first carousel problem is why angular momentum was conserved? there was net external torque present due to the ball sticking on the carousel.
In collisions there will always be net force or net torque on the individual objects. Each object will experience a net torque or force that is equal and opposite to what the other object is experiencing. In the case of the carousel, the dropped ball speeds up and starts to spin while the carousel itself is slowed down a bit. Hopefully this is helpful.
@@HowToPhysics Ok then this should necessarily mean that there is no net external torque on the entire system of carousel and the ball. For angular momentum conservation, we need the net torque to be 0. Ok thanks for the help.
Great question. Both objects would still have the same angular velocity after sticking together. What changes is the moment of inertia. The particle would now have a moment of inertia of I = m(3/5 R)^2 which would be I = (9/25)mR^2 and you would follow the same procedure as before with this new moment of inertia. Hope this helps!
Honestly the Princeton Review books are very helpful I think. They make a new one every year and are about $20 www.princetonreview.com/college-advice/ap-physics-c-exam ... They're not perfect and the questions won't be worded in the same way as actual AP test questions but the content review is very straightforward and helpful!
Your teaching style is very helpful, it makes these topics seem less complicated. Thanks! Also: Why does the point mass have initial angular momentum in the second problem but not the first one? Is it because it started with a velocity?
Thank you! And yes, you can think of it as linear momentum turning into angular momentum too if that helps. I agree that it's a little weird to say that an object moving in a straight line has angular velocity :)
thank you
one thing i did not get in the first carousel problem is why angular momentum was conserved? there was net external torque present due to the ball sticking on the carousel.
In collisions there will always be net force or net torque on the individual objects. Each object will experience a net torque or force that is equal and opposite to what the other object is experiencing. In the case of the carousel, the dropped ball speeds up and starts to spin while the carousel itself is slowed down a bit. Hopefully this is helpful.
@@HowToPhysics
Ok then this should necessarily mean that there is no net external torque on the entire system of carousel and the ball. For angular momentum conservation, we need the net torque to be 0. Ok thanks for the help.
What if the mass of the particle was dropped not onto the edge but a little bit inside the disk? Like when a particle is dropepd at 3/5 R ?
Great question. Both objects would still have the same angular velocity after sticking together. What changes is the moment of inertia. The particle would now have a moment of inertia of I = m(3/5 R)^2 which would be I = (9/25)mR^2 and you would follow the same procedure as before with this new moment of inertia. Hope this helps!
Do you know any good resources to self-study ap physics c mechanics? Or in general review for the ap exam?
Honestly the Princeton Review books are very helpful I think. They make a new one every year and are about $20 www.princetonreview.com/college-advice/ap-physics-c-exam ... They're not perfect and the questions won't be worded in the same way as actual AP test questions but the content review is very straightforward and helpful!
@@HowToPhysicsThank you! I will for sure check that out.
Your teaching style is very helpful, it makes these topics seem less complicated. Thanks!
Also: Why does the point mass have initial angular momentum in the second problem but not the first one? Is it because it started with a velocity?
Thank you! And yes, you can think of it as linear momentum turning into angular momentum too if that helps. I agree that it's a little weird to say that an object moving in a straight line has angular velocity :)
NBICE
use colors next time
Great suggestion!