Work, energy and powerAQA A-Level Physics: Mind map

Exam questions on Work, energy and power

1. A student pulls a suitcase across a level floor using a handle. The handle makes an angle of 30° above the horizontal and the force in the handle is a constant 40 N. The suitcase moves 25 m along the floor in 20 s.
   The student raises the handle so that it makes an angle of 60° above the horizontal, with the same force and distance. State and explain the effect on the work done.2 marks
2. A car travels along a straight, level road at a constant speed of 25 m s⁻¹. The total resistive force on the car is 600 N. The engine's fuel supplies energy at the rate of 60 kW.
   Calculate the efficiency of the car's engine and drive system.2 marks
3. A crate of mass 20 kg is at rest on a smooth horizontal floor. A horizontal force pushes the crate in a straight line. The force increases uniformly from 0 to 80 N over the first 5.0 m of the crate's motion, then stays constant at 80 N for a further 3.0 m. Friction is negligible.
   State the significance of the area under a force-displacement graph and calculate the work done on the crate in the first 5.0 m.3 marks