A pellet with a mass m is fired with an initial speed vo into a wooden block of mass M
suspended at the end of a light string of length L. After the pellet strikes the block, it
becomes embedded in the block and caused the block to move to the right and the string to deflect from the vertical by an angle θ.

a. Determine the velocity of the block after the collision.
b. Determine the change in the kinetic energy of the system during the
collision.
c. Determine the angular displacement of the string.
d. What is the initial speed of the pellet if the string deflects by θ = 90°?

(Answers attached below, not sure how to get to them)