physics question

Question

You keenly measure the angular momentum of a ball of mass 0.405 kg to have a magnitude of 16.7 kg·m²/s. The ball is 7.93 m away from you and its direction of motion makes an angle of 17.38 degrees with respect to your line of sight. What is it speed?

Answer 1

Given

m = 0.405 kg

L = 16.7 kg*m^2/s

r = 7.93 m

Find: V

Solution:

Through cross product we are able to reduce the angular momentum equation to the following. Angular momentum points out of the page when you cross the r vector to the velocity in the direction of the angular velocity.

L = mrV = mrVsinθ

16.7 = 0.405 * 7.93 * Vsin(17.38)

Solve for V = 17.40 m/s

Please note: A diagram to this solution would help clarify the concepts.