Lesson 2.6.3
2.6.3 Power and efficiency Quiz: Pearson Edexcel Physics, Unit 2
20 questions
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Lesson 2.6.3, Power and efficiency: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 2: Mechanics, written with Revision Ninja.
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The 20 questions
-
What is defined as the rate of transfer of energy?
- Work done
- Momentum
- Force
- Power
-
Which unit is the SI unit of power?
- Joule
- Newton
- Pascal
- Watt
-
Efficiency is calculated as useful energy output divided by what?
- Total energy input
- Useful energy input
- Wasted energy output
- Total power output
-
A motor lifts a 50 kg load through 10 m in 5.0 s, at constant speed. What is the useful power output, taking g = 9.8 m s^-2?
- 490 W
- 980 W
- 98 W
- 9800 W
-
A motor has a power input of 1500 W and a power output of 1200 W. What is its efficiency?
- 80%
- 75%
- 125%
- 20%
-
A kettle has a power rating of 2000 W and is 80% efficient. What is its useful power output?
- 400 W
- 2000 W
- 1600 W
- 2500 W
-
A pump moves 1200 kg of water up 15 m in 60 s. What is the power needed to do this, taking g = 9.8 m s^-2?
- 29 kW
- 2.9 kW
- 0.29 kW
- 294 W
-
A device has an efficiency of 25% and a total power input of 800 W. What is its useful power output?
- 3200 W
- 25 W
- 200 W
- 800 W
-
An electric car applies a driving force of 500 N while moving at 20 m s^-1. What is the power output of the motor?
- 25 kW
- 500 W
- 10 kW
- 1 kW
-
A motor takes 240 W of input and raises a 10 kg mass at a steady 0.50 m s^-1. What is its efficiency, taking g = 9.8 m s^-2?
- 4.9%
- 80%
- 49%
- 20%
-
Machine X (60% efficient, 1 kW input) and Machine Y (40% efficient, 1.5 kW input) share what?
- Percentage efficiency
- Total power input
- Useful power output
- Wasted power output
-
A car moves at a constant 25 m s^-1 against a total resistive force of 800 N. What power must the engine deliver?
- 32 kW
- 20 kW
- 800 W
- 2 kW
-
Which law prevents the efficiency of any device from exceeding 100%?
- Conservation of energy
- Conservation of momentum
- Ohm's law
- Hooke's law
-
A lift of mass 500 kg rises at a constant 2.0 m s^-1. What is the power needed, taking g = 9.8 m s^-2?
- 98 kW
- 9.8 kW
- 1.0 kW
- 980 W
-
A 40 kW engine does 2.0 MJ of work. How long does this take?
- 500 s
- 0.02 s
- 80 s
- 50 s
-
A machine has a useful power output of 300 W and an efficiency of 60%. What is the total power input?
- 500 W
- 600 W
- 180 W
- 360 W
-
Which relationship gives the power of a force F acting on an object moving at constant velocity v in the direction of F?
- P = F^2 v
- P = Fv^2
- P = F/v
- P = Fv
-
A wind turbine's useful electrical output is 1.2 MW and its input power from the wind is 4.0 MW. What is its efficiency?
- 80%
- 120%
- 3.3%
- 30%
-
A cyclist produces 200 W of power and travels at constant speed, overcoming a 40 N resistive force. What is the cyclist's speed?
- 5.0 m s^-1
- 0.20 m s^-1
- 8000 m s^-1
- 40 m s^-1
-
A machine's total energy input is 2000 J and its wasted energy is 1700 J. What is its efficiency?
- 1700%
- 120%
- 85%
- 15%
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