Answer:
Explanation:
Since the block is at rest in an elevated position, we can assume that it only has potential energy.
U=mgh is the formula for potential energy where U=potential energy, m= mass, g=acceleration due to gravity, and h=height.
Plug in known variables....
U=4kg*9.8m/s^2*20m
U=784 joules of potential energy or letter A.
