Answer:
a) Kinetic energy decreases, b) Potential energy increases, c) Mechanical energy stays constant, d) Kinetic energy increases, e) Kinetic energy increases, f) Mechanical energy stays constant.
Explanation:
a) Let suppose that the skater is a conservative system. If he goes up the hill, gravitational potential energy is increased at the expense of kinetic energy. In a nutshell, his kinetic energy decreases.
b) His potential energy increases.
c) Mechanical energy is the sum of gravitational potential and kinetic energies, since skater is conservative, then mechanical energy stays constant.
d) If he goes down the hill, his kinetic energy is increased at the expense of gravitational potential energy. In a nutshell, his kinetic energy increases.
e) His potential energy decreases.
f) Mechanical energy is the sum of gravitational potential and kinetic energies, since skater is conservative, then mechanical energy stays constant.
