6 A car of mass 1300 kg is moving on a straight road.
- On a horizontal section of the road, the car has a constant speed of \(30 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and there is a constant force of 650 N resisting the motion.
- Calculate, in kW , the power developed by the engine of the car.
- Given that this power is suddenly increased by 9 kW , find the instantaneous acceleration of the car.
- On a section of the road inclined at \(\sin ^ { - 1 } 0.08\) to the horizontal, the resistance to the motion of the car is \(( 1000 + 20 v ) \mathrm { N }\) when the speed of the car is \(v \mathrm {~m} \mathrm {~s} ^ { - 1 }\). The car travels downwards along this section of the road at constant speed with the engine working at 11.5 kW .
Find this constant speed.