Question

A small pebble and one large boulder start at the same height and begin rolling down the side of a mountain. Which object would have less kinetic energy as it crashes on the road at the bottom of the mountain? Justify your selection.

Answer 1

The small pebble

Step-by-step explanation:

Since the potential energy, P.E lost equals kinetic energy, K.E gained,

P.E = K.E

P.E = mgh = K.E

So, K.E = mgh where g = acceleration due to gravity and h = height of drop

Since h and g are constant

K.E ∝ m

So, the kinetic energy of the object is directly proportional to its mass. Thus, the object with the smaller mass has the lesser kinetic energy.

Since the object with the smaller mass is the small pebble, so the small pebble would have less kinetic energy as it crashes on the road at the bottom of the mountain.