New
New
Year 10
OCR
Higher

Work done calculations (W = F × s)

I can describe how energy is transferred by a force and calculate the amount.

New
New
Year 10
OCR
Higher

Work done calculations (W = F × s)

I can describe how energy is transferred by a force and calculate the amount.

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Lesson details

Key learning points

  1. Work done is the total amount of energy transferred.
  2. Work done = force x distance (moved in the direction of the force).
  3. Work done is measured in Joule (J).

Common misconception

Pupils often confuse the terms force, energy, and work done and use them interchangeably.

Provide opportunities for pupils to describe events in which the three terms need to be used appropriately, e.g. in describing energy transfers for pushing (force) a crate (doing work) along a level surface (energy transferred).

Keywords

  • Conservation of energy - The law of conservation of energy states that energy cannot be created or destroyed, but it can be transferred.

  • Dissipate - Friction can cause energy to dissipate into the surroundings by heating.

  • Work - Work is done whenever a force makes an object move. The amount of work is force multiplied by distance moved in the direction of the force.

  • Joule (J) - The unit for measuring energy is the joule (J) which is the same as the unit for measuring energy.

  • Kilojoule (kJ) - A thousand joules is called a kilojoule (kJ).

This lesson provides opportunity for pupils to measure forces and distances and to experience what it feels like to do different amounts of work. This can allow them to appreciate better the numbers in the calculations.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
What is the name of the force that acts between two surfaces in contact and in the opposite direction to motion?
drag
Correct answer: friction
pull
tension
Q2.
Which of these pieces of equipment can be used to measure the size of a force?
ammeter
thermometer
metre ruler
Correct answer: newton meter
Q3.
Which of these units is the size of a force measured in?
amps
joules
Correct answer: newtons
watts
Q4.
Which of these forces is a contact force?
Correct answer: air resistance
electrostatic force
gravitational force
magnetic force
Q5.
When a book is lifted and placed on a higher shelf, it has more energy in its store.
Correct Answer: gravitational
Q6.
Match each energy store to the properties that an object has when there is energy in that store.
Correct Answer:Energy in a chemical store ... ,means an object may take part in a chemical reaction.

means an object may take part in a chemical reaction.

Correct Answer:Energy in an elastic store ... ,means an object may stretch and increase in length.

means an object may stretch and increase in length.

Correct Answer:Energy in a gravitational store ...,means an object has mass and is at a position above Earth's surface.

means an object has mass and is at a position above Earth's surface.

Correct Answer:Energy in a kinetic store ...,means an object has mass and is moving.

means an object has mass and is moving.

6 Questions

Q1.
Which two statements describe what happens to energy when it dissipates?
The energy is used up, so there is none left.
Correct answer: The energy spreads out into the surroundings.
Correct answer: The energy is transferred into a thermal store.
The energy is transferred into a chemical store.
Q2.
240 J of energy is transferred from a chemical store to both a gravitational store and a thermal store. If 80 J is transferred to the gravitational store, how much is transferred to the thermal store?
A maximum amount of 160 J.
Correct answer: Exactly 160 J.
A minimum amount of 160 J.
It is impossible to tell.
Q3.
Match the energy values on the left to the equivalent values on the right.
Correct Answer:45 000 J,45 kJ

45 kJ

Correct Answer:4.5 kJ,4500 J

4500 J

Correct Answer:450 J,0.45 kJ

0.45 kJ

Correct Answer:0.045 kJ,45 J

45 J

Q4.
A force of 600 N is used to lift a box above the ground. An identical box is moved three times as high by a force of 200 N. How much work was done lifting the second box compared to the first?
9× less
3× less
Correct answer: the same amount
3× more
9× more
Q5.
Put the statements in order of increasing work done on identical boxes, starting with the least work done.
1 - Moving a box 3 m with a force of 5 N.
2 - Moving a box 2 m with a force of 8 N.
3 - Moving a box 1 m with a force of 17 N.
4 - Moving a box 1.5 m with a force of 12 N.
Q6.
Aisha does 480 J of work pushing a crate 6 m along the floor. What is the size of the force that she pushed the crate with?
Correct answer: 480 ÷ 6 = 80 N
480 N
480 × 6 = 2,880 N