Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Work and Power
58 practice questions
Topics covered
Practice questions
21–29 of 29 · Normal
Question 21
1 mark · Normal
Answer and see the solution →State the formula relating power, work done (or energy transferred), and time.
Question 22
3 marks · Normal
Answer and see the solution →A student with a mass of 60 kg runs up a flight of stairs in 9.0 s. The stairs have 12 steps, each 0.25 m high. Use g = 10 N/kg.
Question 23
3 marks · Normal
Answer and see the solution →A cyclist rides up a hill at a constant speed. Explain, using ideas about energy stores and transfers, why the cyclist must keep pedalling to maintain this speed.
Question 24
3 marks · Normal
Answer and see the solution →A table shows the time taken for four students to lift identical boxes through the same vertical distance:
Student Time taken (s) Ali 10 Ben 8 Chloe 12 Dina 6 Each box requires 300 J of work to be lifted.
(a)[1 mark]Which student had the greatest power output?
(b)[2 marks]Calculate the power output for this student.
Question 25
6 marks · Normal
Answer and see the solution →A construction worker lifts a toolbox of mass 12 kg vertically upwards at a steady speed through a height of 2.5 m in 5 seconds.
(a)[2 marks]Calculate the work done by the worker in lifting the toolbox.
(b)[1 mark]State the relationship between work done and energy transferred in this process.
(c)[3 marks]Calculate the power output of the worker while lifting the box.
Question 26
5 marks · Normal
Answer and see the solution →A diver of mass 60 kg jumps from a diving board 8 m above a swimming pool. Ignore air resistance.
(a)[2 marks]Calculate the gravitational potential energy (GPE) that the diver has at the top of the jump, relative to the water.
(b)[3 marks]Assuming all of the GPE is converted to kinetic energy (KE), calculate the speed of the diver just before hitting the water.
Question 27
5 marks · Normal
Answer and see the solution →A small electric cart has a mass of 120 kg and moves at a steady speed of 5 m/s along a horizontal track for 40 m. The total frictional force opposing its motion is 90 N.
(a)[2 marks]Calculate the work done against friction as the cart moves 40 m.
(b)[2 marks]Calculate the kinetic energy of the cart as it moves.
(c)[1 mark]State whether the work done against friction is equal to, less than, or greater than the kinetic energy of the cart. Explain your answer.
Question 28
5 marks · Normal
Answer and see the solution →A 400 kg rollercoaster car starts from rest at the top of a track 15 m above the ground. The car descends to the lowest point with negligible friction. Use g = 10 N/kg.
(a)[2 marks]Calculate the gravitational potential energy of the car at the top of the track.
(b)[3 marks]Calculate the speed of the car at the lowest point, assuming all the potential energy changes to kinetic energy.
Question 29
6 marks · Normal
Answer and see the solution →A student with weight 500 N runs up a set of stairs 4 m high in 10 s.
(a)[2 marks]Calculate the work done against gravity as the student climbs the stairs.
(b)[2 marks]Calculate the student's power output while running up the stairs.
(c)[2 marks]Describe one reason why the actual useful power output of the student might be less than the calculated value.