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Year 9

Hooke's law

I can describe and explain the relationship between the extension of a spring and the force stretching it.

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New
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Year 9

Hooke's law

I can describe and explain the relationship between the extension of a spring and the force stretching it.

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Share activities with pupils
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Lesson details

Key learning points

  1. A line of best fit can show the relationship between variables clearly.
  2. The extension of a spring increases the same amount for each equal sized increase in force.
  3. The extension of a spring is directly proportional to the force applied.
  4. A spring is elastic because it returns to its original length when a force is removed.
  5. Hooke's law describes the behaviour of springs.

Keywords

  • Line of best fit - A line of best fit passes between a set of data points on a graph to show the pattern.

  • Directly proportional - Variables are directly proportional when one is a constant multiple of the other.

  • Elastic - A spring is elastic when it returns to its original length after forces are removed from it.

  • Hooke's law - Hooke's law describes the behaviour of a spring when it is stretched.

Common misconception

The line of a graph must go through all of the points.

Get pupils to invent plots to add to a graph showing a line of best fit that include small mistakes in the measurements.


To help you plan your year 9 science lesson on: Hooke's law, download all teaching resources for free and adapt to suit your pupils' needs...

Pupils do not need to know the Hooke's law equation (F = ke). If pupils have collected data in prior lessons they should plot graphs using that, this will allow multiple springs to be compared helping to verify the law.
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Adult supervision required

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Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Starter quiz

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6 Questions

Q1.
Complete the statement. The word used to describe the force on an object due to a gravitational field is ...
Correct Answer: weight, the weight, weight.
Q2.
A pupil puts different forces on a spring. Starting with the smallest extension, sort the forces into order of the extension they cause.
1 - 1.0 N
2 - 1.5 N
3 - 2.0 N
4 - 2.5 N
5 - 3.0 N
6 - 6.0 N
Q3.
The figure shows a spring before and after a weight has been added. What is the extension of the spring when the mass is placed on it?
An image in a quiz
0 cm
4.0 cm
Correct answer: 4.5 cm
10.5 cm
14.5 cm
Q4.
The photograph shows a pupil measuring the extension of a spring. How could the pupil improve the accuracy of the measurement?
An image in a quiz
Use a shorter spring to make the extension shorter.
Use a longer ruler to reach the spring.
Correct answer: Use a set square to make sure the measurement is horizontal.
Move the ruler further from the spring to keep it balanced.
Use a longer spring to make the extension shorter.
Q5.
The gravitational field strength on Earth is 10 N/kg. What size mass will have a weight of 1 N?
10 kg
1 kg
1000 g
Correct answer: 100 g
10 g
Q6.
Why is it important to measure the extension of a spring when masses are taken off as well as being added?
This will help loosen the spring and make it stretch better.
The masses may have changed after they were added.
Correct answer: To help check the accuracy of the measurements.
So that a wider range of masses can be used.

Exit quiz

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6 Questions

Q1.
Match the key word or phrase to the definition.
Correct Answer:line of best fit,Passes between data points on a graph to show the pattern.
tick

Passes between data points on a graph to show the pattern.

Correct Answer:directly proportional,When one variable doubles, the other is doubled.
tick

When one variable doubles, the other is doubled.

Correct Answer:elastic,Returns to its original length when the forces are removed.
tick

Returns to its original length when the forces are removed.

Correct Answer:Hooke’s law,A description of the behaviour of springs.
tick

A description of the behaviour of springs.

Q2.
Which statement about springs is correct when they are stretched?
The length doubles for each newton of force.
The extension increases at random.
The extension is independent of the force acting.
Correct answer: The extension increases the same amount for each newton of force.
All springs stretch the same amount per newton.
Q3.
What happens to the extension of a spring if the force acting on it is increased from 6 N to 18 N?
Is is three times smaller.
It halves.
It is the same.
It doubles.
Correct answer: It triples.
Q4.
Which of the following describes the line of best fit for a graph where the two variables are directly proportional?
It is a curve.
Correct answer: It is a straight line.
It is a series of lines that connect all the data points exactly.
It passes close to the origin (0,0).
Correct answer: It passes through the origin (0,0).
Q5.
Some pupils add too much force to a spring. For each extra 1 N they then add, the extension increases much more than expected. What will happen to the spring when the force is removed.
It will spring back to shorter than its original length.
It will spring back to its original length.
Correct answer: It will spring back to longer than its original length.
It will not spring back and stay at the length it has reached.
Q6.
The graph shows the extension of a spring for different forces acting on it. What is the extension per newton for this spring? Give your answer to two significant figures.
An image in a quiz
Correct Answer: 0.33 cm, 0.33, 0.33 centimetres, 0.33 cm/N