# Rotational motion inelastic collision

1. Mar 22, 2013

### kirafreedom

1. The problem statement, all variables and given/known data

A ball of clay of mass m travels with velocity v in a path tangent to a disk of radius R and mass M. The clay collides with the disk tangentially to its outer rim ( a totally inelastic collision) and the clay and disk begins to spin about the axis.
a) What is the final angular speed of the clay and disk ( don't forget to include the mass m after the collision.
b) if the clay had collided with the rim at an angle of 30° to the tangent line what would the final angular speed be then

2. Relevant equations

v'b=v'a
va=v'acosθ+v'bcosθ

3. The attempt at a solution

a)
mva=mv'acosθ+mv'bcosθ
0=mv'asinθ+mv'bsinθ

v'b=-va(sinθ/sin(-θ))
v'a=v'b
=va/2cosθ

b) im not sure without knowinif the formula above is correct

2. Mar 22, 2013

### Simon Bridge

If you are unsure about a formula - try using physics.
What are the laws that the motion has to follow?

3. Mar 23, 2013

### kirafreedom

what do u mean? Newtons law?

4. Mar 23, 2013

### Simon Bridge

You know a whole bunch of physical laws besides Newton's ones.
How many do you know that concern angular momentum and momentum?