Answer:
a) to when all is at rest before firing the ball.
The spring is compressed and elastic potential energy of spring is maximum and kinetic energy of the ball is 0
b) tā, immediately before the collision.
The spring is not compressed and elastic potential energy of spring is 0, however ball has maximum kinetic energy from tāātā, kinetic energy of the ball is increasing and potential energy of spring is decreasing
c) tā, immediately after the collision.
Kinetic energy of the ball and pendulum has decreased and potential energy of combination is 0
d) [tex]t_s[/tex], when all is at rest after the collision.
Potential energy of the system has increased to maximum values and kinetic energy has decreased to 0..