# Question #fbddf

##### 1 Answer

Sep 8, 2017

The mass of the rock is 15 kg if the weight is 147 N. If it is falling, we need more information.

#### Explanation:

The question requires some additional information to understand how the act of falling is significant. The downward force accelerating a falling 15 kg rock is 147 N.

But if the rock produces a force of 147 N when it hits the ground, we would need to know the distance it dropped and how quickly it comes to a stop. That would be given by the equality of the 2 ways to calculate impulse. Change in momentum and Force*time
are both ways to calculate impulse.
Impulse = mass*(final velocity - initial velocity) = average force*time

I hope this helps,

Steve