4. A car starts from rest at a point \(S\) on a straight racetrack. The car moves with constant acceleration for 20 s , reaching a speed of \(25 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). The car then travels at a constant speed of \(25 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) for 120 s . Finally it moves with constant deceleration, coming to rest at a point \(F\).

1. In the space below, sketch a speed-time graph to illustrate the motion of the car. The distance between \(S\) and \(F\) is 4 km .
2. Calculate the total time the car takes to travel from \(S\) to \(F\).
   (3) A motorcycle starts at \(S , 10 \mathrm {~s}\) after the car has left \(S\). The motorcycle moves with constant acceleration from rest and passes the car at a point \(P\) which is 1.5 km from \(S\). When the motorcycle passes the car, the motorcycle is still accelerating and the car is moving at a constant speed. Calculate
3. the time the motorcycle takes to travel from \(S\) to \(P\),
4. the speed of the motorcycle at \(P\).
   (2)