Energy – Forces Doing Work

What Energy – Forces Doing Work covers

Energy – Forces Doing Work is examined in Paper 6, Physics 2. It covers energy stores and energy transfer diagrams, changing a system's energy, and measuring work done, work done and the energy changes it causes, gravitational potential and kinetic energy calculations, dissipation and wasted energy, power as the rate of energy transfer and the watt, and calculating efficiency.

The 7 subtopics

Each one has its own page.

• Energy stores and energy transfer diagramsStore changes for a catapult, a fan, a parachutist, a rocket, a clockwork toy and a bouncing ball, what energy transfer diagrams show, and closed systems.Open →
• Changing a system's energy, and measuring work doneThe three ways a system's energy changes, by forces doing work, electrically and by heating, with examples of each, measuring work done with a newtonmeter and a distance, and work done as energy transferred in joules.Open →
• Work done and the energy changes it causesThe work done equation with force and distance calculations, why the distance is along the force, and the store changes when work lifts, drives, brakes or stretches something.Open →
• Gravitational potential and kinetic energy calculationsGravitational potential energy from mass, field strength and height, why lifting work equals the gain, kinetic energy from mass and speed, and finding speed or mass from an energy.Open →
• Dissipation and wasted energyFriction and heating in bicycle gears, lift motors, car engines, drills and tyres, where dissipated energy goes, and why warming a machine's own parts is wasteful.Open →
• Power as the rate of energy transferPower as energy transferred each second, comparing motors, cranes and heaters, the watt, the power equation, and calculations from work done and time.Open →
• The watt, and calculating efficiencyOne watt as one joule per second, energy from power and time, and efficiency from useful and total energy or power, as a decimal or a percentage.Open →

What you need to know

Answer each one before you reveal it.

Take Energy – Forces Doing Work further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Work done vs Power

  Work done: force multiplied by the distance moved in the direction of the force, in joules. Power: the rate at which energy is transferred, measured in watts.

• Joule vs Watt

  Joule: the unit of energy transferred and of work done. Watt: the unit of power, the energy transferred each second.

• Kinetic store vs Gravitational potential store

  Kinetic store: the store filled when a force sets an object moving. Gravitational potential store: the store filled when an object is lifted against gravity.

Questions from this topic

Each one with the model answer underneath.

1. 1

   Describe the change in energy stores when a stretched catapult launches a stone.

   Model answer

   Energy is transferred from the elastic potential store of the catapult to the kinetic store of the stone.

2. 2

   Describe the change in energy stores when a battery-powered fan is switched on.

   Model answer

   Energy is transferred from the chemical store of the battery to the kinetic stores of the blades and the moving air.

3. 3

   Describe the change in energy stores while a parachutist falls at a steady speed.

   Model answer

   The gravitational potential store empties into the thermal store of the air, while the kinetic store stays the same.

4. 4

   Describe the change in energy stores when fuel burns in a rocket engine during a launch.

   Model answer

   Energy is transferred from the chemical store of the fuel to the kinetic and gravitational potential stores of the rocket.

5. 5

   Describe the change in energy stores when a wound-up clockwork toy runs across the floor.

   Model answer

   Energy is transferred from the elastic potential store of the spring to the kinetic store of the toy.

6. 6

   Describe the change in energy stores as a bouncing ball rises after hitting the ground.

   Model answer

   Energy is transferred from the elastic potential store of the squashed ball to its kinetic and gravitational potential stores.

What is inside Levo

Six ways to work the same material.

Energy – Forces Doing Work revision questions

What does Energy – Forces Doing Work cover in Edexcel GCSE Combined Science Physics?

7 subtopics: energy stores and energy transfer diagrams, changing a system's energy, and measuring work done, work done and the energy changes it causes, gravitational potential and kinetic energy calculations, dissipation and wasted energy, power as the rate of energy transfer and the watt, and calculating efficiency. Each one has its own page with questions and model answers.

How is Energy – Forces Doing Work organised?

By the Edexcel 1SC0 specification, subtopic by subtopic, so it matches the order you are taught it in.