4. A car moves in a straight line from \(P\) to \(Q\), a distance of 420 m , with constant acceleration. At \(P\) the speed of the car is \(8 \mathrm {~ms} ^ { - 1 }\). At \(Q\) the speed of the car is \(20 \mathrm {~ms} ^ { - 1 }\). Find

1. the time taken to travel from \(P\) to \(Q\),
2. the acceleration of the car,
3. the time taken for the car to travel 240 m from \(P\). Given that the mass of the car is 1200 kg and the tractive force of the car is 900 N ,
4. find the magnitude of the resistance to the car's motion. \section*{MECHANICS 1 (A) TEST PAPER 3 Page 2}