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# Physics question help!!! watch

1. A vehicle is travelling at 24ms-1 and then decelerates uniformly. It travels 48m during braking before coming to rest:

Calculate:
*The average speed during deceleration
*The time taken before coming to rest
*The deceleration of th evehicle

If the vehicle is now travelling with twice the speed, then comes to rest with the same decelaration, calculate:

*The new time taken before coming to rest
*The distance travelled whilst braking

2. You need to use the constant acceleration formulae, suvat.

http://en.wikipedia.org/wiki/Equations_of_motion

You know "u", the starting velocity and you know "v", the ending velocity (it is zero as the vehicle is coming to rest). And you know s, the displacement. You can calculate "a" from these three by equation (5) on the wiki page.

For the second question you know v and u again and now you also know a so you can use (1) to find the time and then (3) to find the distance.

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Updated: January 19, 2010
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