6. The engine of a car of mass 1200 kg is working at a constant rate of 90 kW as the car moves along a straight horizontal road. The resistive forces opposing the motion of the car are constant and of magnitude 1800 N .
- Find the acceleration of the car when it is travelling at \(20 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).
- Find, in kJ, the kinetic energy of the car when it is travelling at maximum speed.
The car ascends a hill which is straight and makes an angle \(\alpha\) with the horizontal. The power output of the engine and the non-gravitational forces opposing the motion remain the same.
Given that the car can attain a maximum speed of \(25 \mathrm {~ms} ^ { - 1 }\),
- find, in degrees correct to one decimal place, the value of \(\alpha\).
(5 marks)