Pearson Edexcel International GCSE (9–1) · PHYSICS · Section
Power
18 practice questions
Practice questions
11–18 of 18
Question 11
3 marks · Normal
Answer and see the solution →A lift with passengers has a combined weight of 3500 N. The lift rises vertically at a constant speed of 2.5 m/s.
(a)[1 mark]State the upward force needed to keep the lift moving at constant speed.
(b)[2 marks]Calculate the power output of the lift motor.
Question 12
1 mark · Normal
Answer and see the solution →State the formula relating power, work done (or energy transferred), and time.
Question 13
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 14
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 15
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 16
5 marks · Hard
Answer and see the solution →A passenger lift of mass 800 kg carries 5 people each of mass 60 kg to a height of 18 m in 22 s. Assume the upward force from the cables exactly balances the total weight as the lift moves at constant speed.
(a)[1 mark]Calculate the total weight lifted by the cables.
(b)[2 marks]Calculate the work done on the lift and passengers in raising them to the top floor.
(c)[2 marks]Calculate the power developed by the lift motor.
Question 17
4 marks · Hard
Answer and see the solution →A bungee jumper leaps from a bridge, attached securely to an elastic cord. Describe in detail how energy is transferred between stores from the moment the jumper steps off the platform until the lowest point of the jump, including where energy is not conserved as useful energy. Refer to named energy stores and describe at least three distinct transfers in your answer.
Question 18
5 marks · Hard
Answer and see the solution →A 0.25 kg ball is dropped from a balcony 25 m above the ground. Ignore air resistance.
(a)[2 marks]Calculate the gravitational potential energy lost by the ball as it falls.
(b)[2 marks]Determine the speed of the ball just before it hits the ground.
(c)[1 mark]Explain why, in real life, the ball’s speed might be less than your calculation.