7 A car of mass 600 kg travels along a straight horizontal road starting from a point \(A\). The resistance to motion of the car is 750 N .
- The car travels from \(A\) to \(B\) at constant speed in 100 s . The power supplied by the car's engine is constant and equal to 30 kW . Find the distance \(A B\).
- The car's engine is switched off at \(B\) and the car's speed decreases until the car reaches \(C\) with a speed of \(20 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). Find the distance \(B C\).
- The car's engine is switched on at \(C\) and the power it supplies is constant and equal to 30 kW . The car takes 14 s to travel from \(C\) to \(D\) and reaches \(D\) with a speed of \(30 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). Find the distance \(C D\).