levo

Work, Energy and Power

  • 7 subtopics
  • 21 things to know
  • Unit AS 1

What Work, Energy and Power covers

Work, Energy and Power is examined in Unit AS 1, Forces, Energy and Electricity, and drawn on again in Unit AS 3, Practical Techniques and Data Analysis. It covers work done and energy transfer, calculating work done, including forces at an angle, gravitational potential energy, kinetic energy, conservation of energy and energy exchanges, work done by a resultant force and change in kinetic energy and power, efficiency and energy use in society.

Where it is assessed

Unit AS 1

Forces, Energy and Electricity, and again in Unit AS 3, Practical Techniques and Data Analysis.

Check the CCEA specification ↗

The 7 subtopics

Each one has its own page.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Why does a person holding a heavy suitcase at rest become tired even though the physics definition says no work is done on the case?

Key term

State the equation for the work done by a constant force that is not along the line of motion, and define every symbol.

Key term

State the equation for the change in gravitational potential energy near the Earth's surface and define every symbol.

Numbers

A climber of mass 65 kg ascends a vertical height of 850 m. Calculate the gain in gravitational potential energy.

Key term

Why can g be quoted either as 9.81 m s⁻² or as 9.81 N kg⁻¹?

Key term

Explain why the kinetic energy of an object can never be negative.

Numbers

A stone is dropped from rest from a height of 20 m. Calculate its speed just before it lands, ignoring air resistance.

Numbers

A pendulum bob is released from a position 0.25 m above its lowest point. Calculate its speed at the lowest point, ignoring resistive forces.

Key term

Describe how light gates can be used to investigate the exchange between gravitational potential energy and kinetic energy for a falling body.

Key term

State the equation relating the work done by a constant resultant force to the change in kinetic energy, and define every symbol.

Numbers

A 900 kg car travelling at 30 m s⁻¹ is brought to rest by a constant braking force of 6.0 kN. Calculate the braking distance.

Key term

Why must F in ½mv² − ½mu² = Fs be the resultant force rather than just the applied force?

Key term

Define power and state the equation used to calculate it.

Key term

Show how the equation P = Fv follows from the definition of power.

Numbers

A crane lifts a 400 kg load through 12 m in 15 s. Calculate the useful output power.

Key term

Define the work done by a force.

Key term

Why does the factor cos θ appear in the equation for work done by a force acting at an angle to the motion?

Key term

Define kinetic energy.

Key term

State the SI unit of work and express it in SI base units.

Key term

What is the work done by a force that acts at 90° to the direction of motion?

Key term

State the equation for kinetic energy and define every symbol.

Take Work, Energy and Power further

The same content, four other ways.

Questions from this topic

Each one with the model answer underneath.

  1. 1

    Define the work done by a force.

    Model answer

    The work done by a force is the product of the force and the distance moved in the direction of the force, W = Fs, where W is the work done in joules, F the force in newtons and s the distance moved in the direction of the force in metres.

  2. 2

    State the SI unit of work and express it in SI base units.

    Model answer

    Work is measured in joules, and 1 J = 1 N m = 1 kg m² s⁻².

  3. 3

    What does one joule of work mean in terms of a force and a distance?

    Model answer

    One joule is the work done when a force of 1 N moves its point of application a distance of 1 m in the direction of the force.

  4. 4

    Is work done a scalar or a vector quantity?

    Model answer

    Work done is a scalar quantity, so it has magnitude but no direction, although it can be positive or negative depending on whether the force acts with or against the motion.

  5. 5

    Explain what happens to energy whenever work is done.

    Model answer

    Whenever work is done, energy is transferred from one form or store to another, and the quantity of energy transferred is equal to the work done.

  6. 6

    A crane lifts a steel girder steadily from the ground to the top of a building. Describe the energy transfers taking place.

    Model answer

    Electrical energy supplied to the motor is transferred mainly to the gravitational potential energy of the girder, with some transferred to the internal energy of the motor and cable through resistance and friction.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

Physical Quantities, Scalars and Vectors
Moments and Equilibrium
Linear Motion and Dynamics
Newton's Laws of Motion

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

The quarks and the .
leptonshadronsmesons

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AA current I is a charge q passing in time t.
BThe length l is vt.
CBIl becomes B × (q/t) × vt, which is Bqv.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Coulomb is a quantity of charge.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Work, Energy and Power revision questions

What does Work, Energy and Power cover in CCEA A-Level Physics?
7 subtopics: work done and energy transfer, calculating work done, including forces at an angle, gravitational potential energy, kinetic energy, conservation of energy and energy exchanges, work done by a resultant force and change in kinetic energy and power, efficiency and energy use in society. Each one has its own page with questions and model answers.
How is Work, Energy and Power organised?
By the CCEA 1210 specification, subtopic by subtopic, so it matches the order you are taught it in.

Every question in Work, Energy and Power, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.