# M2 - Energy, Work & Power

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#1
A car of mass 650kg is travelling on a straight road inclined to the horizontal 5 degrees. At a certain point P on the road the car's speed is 15ms^-1. The point Q is 400 metres down the hill from P, and at Q the car's speed is 35ms^-1. For the motion from P to Q, find:

(a) The increase in kinetic energy of the car,
(b)The decrease in gravitational potential energy of the car
(c)Neglecting any resistances to the car's motion, and assuming that the car's engine produces a constant tractive force on the car as it moves down the hill from P to Q, calculate the magnitude of the tractive force and the power of the car's engine when the car is at Q.

So I need to do this without SUVATS (It's homework) and am stuck on the last part, any help is appreciated!
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4 years ago
#2
the increase in KE is the loss of GPE + work done by the engine

work done by engine = tractive force x distance covered going down the slope.

the power will be tractive force x velocity at Q
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