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ariarch
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Homework Statement
A 900kg car is moving up a 15degree inclined slope at 40ms-1. The driver slams on the brakes, skidding to a halt 40m along the road.
Calculate the total work done by the car.
Homework Equations
This is what I am not sure of. As I am not told whether or not the acceleration is constant, I doubt I can use f=ma.
I'm therefore thinking that I can use:
K.E + GPE?
So, W.D = 1/2(mv12-mv22) + mgh
where m = 40sin15
The Attempt at a Solution
I therefore solve, getting total work done as:
1/2(900*402) + 900*9.81*40sin15.
Or do I have to use the vertical component of gravity? I am perplexed, fine mechanics the most difficult part of Physics, and this is driving me mad!
Thank you.