Answer:
(a) -472.305 J
(b) 1 m
Step-by-step explanation:
(a)
Change in mechanical energy equals change in kinetic energy
Kinetic energy is given by

Initial kinetic energy is

Since he finally comes to rest, final kinetic energy is zero because the final velocity is zero
Change in kinetic energy is given by final kinetic energy- initial kinetic energy hence
0-472.305 J=-472.305 J
(b)
From fundamental kinematic equation

Where v and u are final and initial velocities respectively, a is acceleration, s is distance
Making s the subject we obtain
but a=\mu g hence
