9709 P43 - Nov 2023 - Q4
3493
A car has mass 1600 kg.
(a) The car is moving along a straight horizontal road at a constant speed of 24 m/s and is subject to a constant resistance of magnitude 480 N.
Find, in kW, the rate at which the engine of the car is working.
The car now moves down a hill inclined at an angle of \(\theta\) to the horizontal, where \(\sin \theta = 0.09\). The engine of the car is working at a constant rate of 12 kW. The speed of the car is 24 m/s at the top of the hill. Ten seconds later the car has travelled 280 m down the hill and has speed 32 m/s.
(b) Given that the resistance is not constant, use an energy method to find the total work done against the resistance during the ten seconds.
