A-Level Physics H1 Quiz - Energy Power
Name: ____________________
Class: ____________________
Date: ____________________
Score: ________ / 55
Duration: 60 Minutes
Total Marks: 55 Marks
Instructions:
- Answer all questions.
- Show all necessary working for calculation questions.
- Use g=9.81 m s−2 where applicable.
- Give your answers to an appropriate number of significant figures.
Section A: Fundamental Concepts (Questions 1-5)
Short answer and conceptual questions.
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Define the term power in the context of energy transfer. [2]
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State the principle of conservation of energy. [2]
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A force F acts on a body and moves it through a distance d at an angle θ to the direction of motion. Write the expression for the work done by the force. [1]
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Distinguish between useful power output and total power input for a mechanical system. [2]
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A system is said to be "conservative" if the total mechanical energy remains constant. Name two forces that are considered conservative. [2]
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Section B: Mechanical Energy & Work (Questions 6-12)
Calculations and structured responses.
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A block of mass 2.0 kg is pushed 5.0 m across a horizontal floor by a constant force of 20 N acting at 30∘ to the horizontal. Calculate the work done by the force. [3]
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A 0.5 kg ball is thrown vertically upwards with an initial speed of 15 m s−1. Calculate its maximum height, ignoring air resistance. [3]
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A car of mass 1200 kg accelerates from rest to 25 m s−1 in a straight line. Calculate the increase in its kinetic energy. [3]
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A spring with force constant k=500 N m−1 is compressed by 0.10 m.
(a) Calculate the elastic potential energy stored in the spring. [2]
(b) If this energy is used to launch a 0.05 kg pellet, calculate the launch speed. [2]
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A 10 kg object slides down a frictionless inclined plane of height 4.0 m and angle 30∘. Calculate the speed of the object at the bottom of the plane. [3]
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A constant force of 15 N acts on a 3.0 kg mass initially at rest. Calculate the work done by the force after the mass has moved 4.0 m. [2]
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Explain why the actual height reached by a projectile is always less than the theoretical height calculated using conservation of mechanical energy when air resistance is present. [3]
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Section C: Power, Efficiency & Applications (Questions 13-20)
Advanced calculations and system analysis.
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An electric motor lifts a 50 kg crate at a constant speed of 0.8 m s−1. Calculate the useful power output of the motor. [3]
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The motor in Question 13 has a total power input of 500 W. Calculate the efficiency of the motor. [3]
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A pump moves water from a depth of 10 m to a tank at a rate of 0.2 kg s−1. Calculate the minimum power required by the pump. [3]
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A car of mass 1500 kg travels at a constant speed of 20 m s−1. The total resistive force (air resistance and friction) is 600 N. Calculate the power developed by the engine to maintain this speed. [3]
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A 2.0 kW electric heater is used to heat 1.0 kg of water. If the heater is 80% efficient, calculate the energy transferred to the water in 2.0 minutes. [4]
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A roller coaster car of mass 400 kg starts from rest at the top of a hill of height 30 m.
(a) Calculate the theoretical speed at the bottom of the hill. [2]
(b) If the actual speed is 20 m s−1, calculate the energy lost to friction and heat. [3]
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A crane lifts a load of 200 kg through a vertical height of 15 m in 10 s. Calculate the average power output of the crane. [3]
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A light bulb is rated at 60 W and 240 V. If the bulb is used for 5 hours, calculate the total electrical energy consumed in Joules. [3]
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