# How to solve problems on collisions with rotation?

Aravind Bommera
36 Points
11 years ago

Refer http://faculty.northseattle.edu/deyres/physics101/r_solve.htm

They given solutions very clearly,hope you will understand.

All d Best!!!!

yours katarnak Suresh
43 Points
11 years ago

# Conservation of angular momentum and collisions of rotating bodies-will give full karma points!

Ok so my friend and I are here and neither of us canget this question we both have tried working it out and we just cannot figure it out.  Can someone please help us?  I willgive full karma points I promise if an answer can be found

Learning Goal:
To understand how to use conservation ofangular momentum to solve problems involving collisions of rotatingbodies.
Consider a turntable to be a circular disk ofmoment of inertia. Consider a turntable to be a circular disk ofmoment of inertia rotating at a constant angular velocity  around an axis through the center and perpendicular tothe plane of the disk (the disk''s "primary axis of symmetry"). Theaxis of the disk is vertical and the disk is supported byfrictionless bearings. The motor of the turntable is off, so thereis no external torque being applied to the axis.
Another disk (a record) is dropped onto the first such that itlands coaxially (the axes coincide). The moment of inertia of therecord is . The initial angular velocity of the second disk iszero.

There is friction between the two disks.

After this "rotational collision," the disks will eventually rotatewith the same angular velocity.
Part A.
What is the final angular velocity,, of the two disks?
Expr
Part B
Because of friction, rotational kineticenergy is not conserved while the disks'' surfaces slip over eachother. What is the final rotational kinetic energy, , of the two spinning disks?
Express the final kinetic energy interms of , , and the initial kinetic energy  of the two-disk system. No angular velocitiesshould appear in your answer.