1.1. A lorry of mass 8000 kg is travelling along a straight horizontal road with its engine working at a constant rate of 44 kW.  

By first finding the driving force, find the resistance to the lorry’s motion at the instant when the lorry’s speed is 11 m s^-1 and its acceleration is 0.4 m s^-2.

1.2. Given that the resistance to motion on the lorry is constant, 

i) find the speed of the lorry at the instant when it is travelling with acceleration 0.6 m s^-2,

ii) find the acceleration of the lorry at the instant when it is travelling with speed 20 m s^-1.

1.3. Use your answers to part (b) to describe the relationship between the speed and the acceleration of the lorry whilst its engine is working at a constant rate of 44 kW.