Final answer:
The rock's potential energy is 10,500 J.
Step-by-step explanation:
Gravitational potential energy of an object is given by the equation: P.E. = mgh, where m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object above a reference point.
In this case, the rock has a mass of 25 kg and is on a cliff 42 m high.
Given g = 10 m/s², we can calculate the rock's potential energy as:
P.E. = (25 kg) (10 m/s²) (42 m)
= 10,500 J.