A circular round disc that has a radius of 5cm and a mass of 32g is rotating with an angular velocity of w. A second disc with the same radius but with half of the mass is dropped onto the rotating disc . The two discs slide against eachother till they both have the same final angular velocity

Question

calculate the final angular velocity of the discs
calculate the percentage of the initial KE lost during the collision

Answer 1

1/2 M*W*.05^2=1/2M*w*.05^2+1/2(M/2)*w*.025^2

find w in terms of the original W