9709 P42 - Mar 2021 - Q2
3410
A car of mass 1400 kg is travelling at constant speed up a straight hill inclined at \(\alpha\) to the horizontal, where \(\sin \alpha = 0.1\). There is a constant resistance force of magnitude 600 N. The power of the car’s engine is 22 500 W.
(a) Show that the speed of the car is 11.25 m s\(^{-1}\).
The car, moving with speed 11.25 m s\(^{-1}\), comes to a section of the hill which is inclined at 2° to the horizontal.
(b) Given that the power and resistance force do not change, find the initial acceleration of the car up this section of the hill.
