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Worksheets7 Work, Energy & Power
Total questions: 27
Worksheet time: 14mins
Which of the following best describes work in physics?
Energy transferred by force over a distance
Energy stored in an object at rest
Force acting without displacement
The ability to store energy
Calculate the kinetic energy of a 2 kg object moving at 3 m/s.
3 J
6 J
9 J
12 J
What is the SI unit of work?
Newton
Joule
Watt
Horsepower
Which form of energy is associated with the motion of an object?
Potential Energy
Thermal Energy
Kinetic Energy
Elastic Energy
Clarify the term 'elastic potential energy'.
Energy due to height
Energy due to motion
Energy stored in stretched or compressed materials
Energy from chemical reactions
Which statement best explains the first law of thermodynamics?
Energy cannot be created or destroyed, only transformed
Heat can only flow from hot to cold
Energy stored in springs is potential
Efficiency is always 100%
Distinguish between conduction and convection.
Conduction is heat transfer through liquids only, convection is through solids
Conduction is direct contact heat transfer, convection is heat transfer through fluids
Conduction is always faster
Conduction requires motion, convection does not
Potential energy depends on:
Mass and height
Mass and speed
Temperature
Force and displacement
Conservation of mechanical energy applies when:
Heat is added to a system
Work is done on the system
No energy is lost to heat or friction
Energy is destroyed
Which of the following is NOT a mode of heat transfer?
Conduction
Compression
Convection
Radiation
Interpret what happens to potential energy as an object falls freely.
Decreases
Increases
Stays the same
Turns into elastic energy
Which example depicts energy transformation from potential to kinetic energy?
A stretched spring remaining stationary
A rolling ball slowing down
Water stored behind a dam flowing out
Electric heater warming a room
Give an example of elastic potential energy.
Water behind a dam
Compressed spring
Running athlete
Boiling water
The SI unit of power is:
Watt
Joule
Horsepower
Newton
Which of the following expresses the SI unit for work and energy?
Joule
Watt
Newton
Horsepower
Which situation best exemplifies work being done?
Holding a heavy bag stationary
Pushing a box across the floor
Lifting a book and keeping it still
Carrying an object while walking at constant speed
Power is defined as:
Work × Time
Energy × Distance
Work ÷ Time
Force × Velocity
Describe horsepower in relation to watts.
1 horsepower = 1 watt
1 horsepower ≈ 746 watts
1 horsepower = 1000 watts
Horsepower is unrelated to watts
A spring with a spring constant of 200 N/m is compressed by 0.1 m. What is the elastic potential energy stored in the spring?
1 J
2 J
0.5 J
5 J
Efficiency is defined as:
Output Work / Input Work × 100%
Input Work / Output Work × 100%
Work ÷ Time
Energy × Power
Clarify why no machine is 100% efficient.
Due to energy creation
Some energy is always lost as heat due to friction
Perfect machines are used in the industry
Machines are too light to retain energy
The primary function of a pump is to:
Generate heat
Transfer electrical energy
Reduce temperature
Increase fluid pressure
Match the following energy types to examples:
Thermal energy - Hot tea
Kinetic energy - Stretched bow
Potential energy - Moving car
Elastic energy - Falling stone
Estimate the power used when lifting a 200 N weight by 3 m in 2 s.
100 W
200 W
300 W
600 W
Interpret the meaning of 'efficiency = 40%' in a power plant.
40% of input energy is wasted
40% of input energy is converted into useful work
The power plant uses 40 W only
The power output equals input energy
How much work is done to lift a 5 kg object to a height of 3 m? Choose the nearest answer from the following options.
15 J
29 J
49 J
147 J
A 3 kg ball is dropped from a height of 10 m. What is its velocity just before hitting the ground? Choose the nearest answer from the following options.
9.8 m/s
14 m/s
20 m/s
40 m/s
