A car has mass 1250 kg.

1. The car is moving along a straight level road at a constant speed of 36 m s^-1 and is subject to a constant resistance of magnitude 850 N. Find, in kW, the rate at which the engine of the car is working.
2. The car travels at a constant speed up a hill and is subject to the same resistance as in part (i). The hill is inclined at an angle of θ° to the horizontal, where sin θ° = 0.1, and the engine is working at 63 kW. Find the speed of the car.
3. The car descends the same hill with the engine of the car working at a constant rate of 20 kW. The resistance is not constant. The initial speed of the car is 20 m s^-1. Eight seconds later the car has speed 24 m s^-1 and has moved 176 m down the hill. Use an energy method to find the total work done against the resistance during the eight seconds.