A ball weighing 40 g, attached to a thread, is rotated in a horizontal plane at a constant modulus

A ball weighing 40 g, attached to a thread, is rotated in a horizontal plane at a constant modulus of speed equal to 1 m / s. What is the change in the momentum of the ball after it makes a whole revolution; half a turn; one quarter of a turn?

Solution:
p1 = 0, because the ball returned to its original place
p3 = mv: 4 = 0.04 * 1: 4 = 0.01kg * m / s
p2 = 0.02 kg * m / s
Answer: 0 kg * m / s; 0.01 kg * m / s; 0.02 kg * m / s