(a) The potential energy of the rock relative to the base of the cliff can be calculated using the formula for gravitational potential energy:
PE = mgh
where m is the mass of the rock (24.0 kg), g is the acceleration due to gravity (9.8 m/s^2), and h is the height of the cliff (80.0 m).
PE = 24.0 kg * 9.8 m/s^2 * 80.0 m = 15,360 J
(b) The kinetic energy of the rock just before it strikes the ground can be calculated using the formula for kinetic energy:
KE = 0.5 * m * v^2
where m is the mass of the rock (24.0 kg) and v is the velocity of the rock just before it strikes the ground. The velocity can be calculated using the equation of motion for a freely falling object:
v = sqrt(2gh)
v = sqrt(2 * 9.8 m/s^2 * 80.0 m) = 44.72 m/s
KE = 0.5 * 24.0 kg * 44.72 m/s^2 = 507.84 J