Question

A horizontal vinyl record of mass 0.105 kg and radius 0.0757 m rotates freely about a vertical axis through its center with an angular speed of 5.80 rad/s and a rotational inertia of 5.18 x 10-4 kg·m2. Putty of mass 0.0213 kg drops vertically onto the record from above and sticks to the edge of the record. What is the angular speed of the record immediately afterwards?

Answer 1

4.6939 rad/s

Step-by-step explanation:

You have to use the conservation of angular momentum for both objects as an object is spinning and a collision happens. To properly solve, you have to know that the putty and the vinyl have the same angular speed after the putty lands on it and that the putty acts as a point mass so the formula of it's rotational inertia is mr^2.