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Year 9

Stretching rubber

I can investigate the extension of a rubber band, and compare the behaviour to that of a spring.

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New
New
Year 9

Stretching rubber

I can investigate the extension of a rubber band, and compare the behaviour to that of a spring.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. A rubber band is elastic because it returns to its original length when a force is removed.
  2. The extension of a rubber band increases different amounts for each equal sized increase in force.
  3. The extension of a spring is not directly proportional to the force applied.
  4. The extension pattern is explained by the behaviour of molecular chains in the rubber.

Common misconception

Pupils find it challenging to link the shape of a line graph with physical change in the real world.

Compare two sections of the graph, using the amount of extra stretch per newton as a measure of how easy the rubber band is to stretch.

Keywords

  • Extension - The extension of a rubber band is its change in length.

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

  • Elastic - A rubber band is elastic; it returns to its original length after forces are removed from it.

  • Long molecular chains - Rubber contains long molecular chains, that uncoil when it stretches.

Different groups of pupils should test different rubber bands to show that the stretching pattern is the same for all. Some could plan and investigate how the thickness of the band affects how easy it is to stretch.
Teacher tip

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

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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Starter quiz

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6 Questions

Q1.
Complete the sentence: The increase in length of a spring with a force acting on it is the .
Correct Answer: extension
Q2.
Which word is used to describe something that returns to its original shape when the forces acting on it are removed?
bouncy
rubber
Correct answer: elastic
flexible
stiff
Q3.
What is the extension of this spring when a force of 30 N acts on it?
An image in a quiz
0 cm
5 cm
Correct answer: 10 cm
20 cm
25 cm
Q4.
Which of these is a statement of Hooke's law?
The total length of a spring is directly proportional to the force acting on it.
Correct answer: The extension of a spring is directly proportional to the force acting on it.
The extension of a spring is directly proportional to its mass.
The extension of a spring is inversely proportional to the force acting on it.
The total length of a spring is inversely proportional to the force on it.
Q5.
According to the graph, which of these statements are true?
An image in a quiz
Correct answer: The spring obeys Hooke's law for forces below 40 N.
The spring never obeys Hooke's law.
Correct answer: The spring does not obey Hooke's law for forces over 45 N.
The spring does not obey Hooke's law for forces less than 45 N.
The spring obeys Hooke's law for forces above 45 N.
Q6.
A pupil collects the data shown during a spring experiment. Use the data to predict the extension if the force used was 8 N. Give your answer in cm to the nearest whole number.
An image in a quiz
Correct Answer: 32 cm, 32

Exit quiz

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6 Questions

Q1.
Match the keyword or phrase with the explanation.
Correct Answer:elastic,material returns to its original length after forces are removed

material returns to its original length after forces are removed

Correct Answer:extension,the increase in length when a material is stretched

the increase in length when a material is stretched

Correct Answer:directly proportional,when one variable increases, the other increases at the same rate

when one variable increases, the other increases at the same rate

Correct Answer:long molecular chains,the structure of rubber

the structure of rubber

Q2.
An equal force is applied to both ends of a rubber band. What happens to the rubber band?
An image in a quiz
Correct answer: it becomes longer
it becomes shorter
it becomes thicker
Correct answer: it becomes thinner
it starts to move at a constant speed
Q3.
The figure shows a rubber band before and after it has been stretched. What is the extension of the band?
An image in a quiz
0 cm
2.0 cm
Correct answer: 2.5 cm
9.0 cm
12.5 cm
Q4.
Which of the lines on the graph shows the extension of a rubber band when a force is applied?
An image in a quiz
a
b
Correct answer: c
d
Q5.
Which of the following statements describe the extension of a rubber band when it is stretched?
The extension is directly proportional to the force applied.
Correct answer: The rubber band behaves elastically when the force applied is removed.
Correct answer: The extension increases with the force applied.
The rubber band obeys Hooke's law.
The rubber band becomes permanently stretched when a force is applied.
Q6.
Order the following statements to describe the stretching of a rubber band as an increasing force is applied.
1 - The long chain molecules are closely coiled together.
2 - The long chain molecules begin to uncoil but this is difficult at first.
3 - As more force is added, the molecules unwind and become easier to stretch.
4 - The molecules approach their maximum length, becoming more difficult to stretch.
5 - Eventually, the long chain molecules are fully unwound and stretch no further.

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