# A Ball rolls up a Hill

#### Carl_M

A ball rolls at an initial velocity of 4.00 m/s up a hill. 5 seconds later it is rolling down the hill at 6.0 m/s. <---- What does the question mean? Did the ball roll up for 5 seconds and then started rolling down?

Find its acceleration
Find its displacement at 5.0s

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#### mgb_phys

Homework Helper
Assume it didn't start at the bottom - so it mght be doing 6.0m/s below where it started

#### Carl_M

So did the ball go up 4.00 m/s for 5 secs or go up the hill for 20 meters and then started to roll down at 6 m/s?

#### lanedance

Homework Helper
the ball will be decelarating due to gravity then begins rolling downhill at increasing speed

I think you could assume the hill is at a constant angle so the component of gravity causing the acceleration is constant at g.cos(theta) for whatever theta is...

you know a time and a change in velocity so you should be able to get to what that acceleration is ...

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