Question

A boulder has just finished rolling down a hill and is now on flat ground. If the boulder is moving at 30 m/s when it reaches the flat ground and slows down to a roll of 5 m/s with a deceleration of -5m/s2, how long did it take to decelerate?

Answer 1

We’re given V1, V2, and a (acceleration) and required to find time. We can use the formula for finding acceleration:
a = v2-v1/t
We can then rearrange to find time and input our values.