Work Done

Each round has ten questions. Standard questions 1 and 2 ask you to calculate work from whole-number force and distance values. Question 3 asks you to rearrange W = Fs to find force. Question 4 asks you to find distance. Question 5 gives distance in centimetres, then question 6 gives distance in kilometres. Question 7 gives work in kilojoules and asks for force, so convert the work to joules. Question 8 asks which energy store gains energy when work is done against friction. Question 9 shows a force and a diagonal movement. Question 10 is another W = Fs calculation.

Challenge uses the same first eight question types. Question 9 asks you to calculate work done when lifting a load. It gives g as 9.8 N/kg and a height in centimetres. Question 10 uses the direction diagram to choose the distance along the force. Later questions add unit conversions and questions about energy and direction. Challenge also adds lifting.

Choose one of four answers. Each number includes its unit. Store and direction answers have no unit. Read the worked method after every answer. A right answer scores 10 points. The 15-second clock adds 5 points for a quick answer. In Standard, the question stays open when the bonus ends. In Challenge, an unanswered question locks at zero and counts as wrong. Turn on Practice mode to remove the clock. You can press 1 to 4 to choose, then Enter to continue after the method appears.

Your best score stays on this device, with a separate score for Challenge. For another calculation, use the work done equation page to enter a force, distance or work value and see the rearrangement.

Work is done when a force moves an object. The equation is W = Fs: work done equals force multiplied by distance moved along the force. W is measured in joules (J), F in newtons (N) and s in metres (m). AQA writes the distance as s. Pearson Edexcel often writes d. One joule is one newton-metre, so 1 J = 1 N m.

Work done is equal to the energy transferred. When a force works against friction, energy transfers to the thermal store. The object and nearby surfaces warm up. For example, pushing a box across a rough floor transfers energy to the box and floor as they rub together. The Energy Stores game gives more practice naming stores and transfers.

Use only the distance moved in the direction of the force. If you push a box along a floor, use the distance along the floor. A movement at right angles to the push does not add to work done by that push. For a straight lift, use the vertical height moved against the weight. The diagram in the game shows the force and movement directions without giving a number to calculate.

When a load rises at a steady speed, the work done against its weight is the gain in gravitational potential energy. You can use W = weight × height or W = mgh. Mass must be multiplied by gravitational field strength to find weight. The question gives g in newtons per kilogram, and height must be in metres. Our weight equation page shows how mass and weight are related.

The work done topic appears in AQA Physics 8463 section 4.5.2 and AQA Combined Science 8464 section 6.5.2. Lifting links to AQA sections 4.1.1.2 and 6.1.1.2. Pearson Edexcel Physics 1PH0 and Combined Science 1SC0 cover work and energy transfer in points 8.5 to 8.8. OCR Gateway Physics A J249 covers work in P2.2m-n and P7.1c-d, with lifting in PM2.3iv. OCR Combined Science A J250 covers work in P2.2l-m and P5.1c-e, with lifting in PM2.3iv. Read the AQA Physics specification, AQA Combined Science specification, Pearson Physics specification, Pearson Combined Science specification, OCR Physics A specification and OCR Combined Science A specification.

• Write down what the question asks for before choosing an equation.
• For work done, multiply force in newtons by distance in metres.
• For force or distance, divide work done by the other value.
• Convert centimetres to metres by dividing by 100.
• Convert kilometres to metres by multiplying by 1000.
• Convert kilojoules to joules by multiplying by 1000.
• Check that your answer ends in J, N or m as the question asks.

For a lift, work out the weight first with weight = mass × g, then multiply by the height. Keep the units beside each value while you substitute them. If friction or a distance direction appears in the question, check which way the force acts before you use W = Fs. The Stopping Distance and Terminal Velocity games also use forces and energy transfer.