5. A car on a straight test track starts from rest and accelerates to a speed of \(V \mathrm {~m} \mathrm {~s} ^ { - 1 }\) in 6 seconds. The car maintains this speed for a further 50 seconds before decelerating to rest. In a simple model of this motion, the acceleration and deceleration are assumed to be uniform and the magnitude of the deceleration to be 1.5 times that of the acceleration.

1. Show that the total time for which the car is moving is 60 seconds.
2. Sketch a velocity-time graph for this journey. Given that the total distance travelled is 1320 metres,
3. find \(V\). In a more sophisticated model, the acceleration is assumed to be inversely proportional to the velocity of the car.
4. Explain how the acceleration would vary during the first six seconds under this model.
   (2 marks)