# Acceleration/deceleration problem

If a ball is rolled up a ramp at initial velocity 12 m/s and decelerates at a rate of 2 m/s2, then does the ball run back down the ramp with an acceleration equal to the deceleration?

The incline is 36 m long and it takes 6 seconds to reach the position where the final velocity is zero.

## Answers and Replies

quasar987
Science Advisor
Homework Helper
Gold Member
What would you say? First of all, what is the force that is the cause of the deceleration of the block?

Well, its gravity that causes the deccelration up the ramp, so i would think its gravity that causes the acceleration down the ramp too, but i'm not 100% sure(mostly though).

Gokul43201
Staff Emeritus
Science Advisor
Gold Member
Since there is no mention of friction, one must assume that gravity is the only force involved that can cause the deceleration of the ball. Remember, there is one more force, but it only acts normal (perpendicular) to the inclined plane.

So, yes, the acceleration downslope should equal the deceleration upslope.

quasar987
Science Advisor
Homework Helper
Gold Member
That is indeed correct.

IMO, the exercice was only intended to make you realize that 'deceleration' is only a word for "acceleration that slows down the speed".