Question

If a rock weighing 2,200 N is dropped from a height of 15 m, what is its KE just before it hits the ground? Remember, weight is measured in newtons (N), and is equal to mass times gravity.

A. 0 J
B. 2,224 J
C. 147 J
D. 33,000 J

Answer 1

This is a question conservation of energy. That is;
Potential energy = Kinetic energy

mgh = 1/2*mv^2 = KE

Therefore,
KE = mgh = (2200/9.81)*9.81*15 = 2200*15 = 33000 J

The correct answer is D.