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Forces and elasticity: GCSE Combined Science Physics practice questions

Foundation and Higher · Grade 5

A second set of questions on forces and elasticity. They are different from the ones on the topic page. Try each, then open the answer and compare your working.

More questions

Question 1 Hard

A spring with a spring constant of 50 N/m is stretched by 0.2 m. Work out the energy stored.

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Answer: 1 J

  1. energy = 0.5 × spring constant × extension²
  2. 0.5 × 50 × 0.04 = 1 J

Question 2 Hard

A spring with a spring constant of 200 N/m is stretched by 0.1 m. Work out the energy stored.

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Answer: 1 J

  1. energy = 0.5 × spring constant × extension²
  2. 0.5 × 200 × 0.01 = 1 J

Question 3 Hard

The extension of a spring is doubled. State what happens to the energy stored and explain why.

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Answer: It becomes four times as big, because the energy depends on the extension squared.

  1. energy depends on extension squared.
  2. Doubling the extension makes the energy four times as big.

Question 4 Hard

A student stretches a spring beyond its limit of proportionality and then releases it. Describe what happens to the spring.

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Answer: The spring does not return to its original length.

  1. The distortion is no longer fully elastic.
  2. The spring does not go back to its original length.

Question 5 Medium

A force-extension graph is a straight line through the origin. Is the relationship linear or non-linear?

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Answer: linear

  1. A straight line through the origin means proportional.
  2. The relationship is linear.

Quick checks

Short questions with options. Choose one before you open the answer.

Check 1

What is the extension of a spring?

  1. The extra length compared with the natural length
  2. The whole length of the stretched spring
  3. The force on the spring
Show answer

The extra length compared with the natural length The increase in length compared with the natural length.

Check 2

What is the natural length of a spring?

  1. Its length when it is fully stretched
  2. Its length with no force on it
  3. Its length in metres
Show answer

Its length with no force on it Its length when no force is acting on it.

Check 3

How many forces are needed to stretch a spring?

  1. One
  2. Three
  3. Two
Show answer

Two At least two, one at each end.

Check 4

What is elastic distortion?

  1. It returns to its original shape
  2. The object stays changed
  3. The object breaks
Show answer

It returns to its original shape The object returns to its original shape when the force is removed.

Check 5

What is inelastic distortion?

  1. The object returns to its shape
  2. It stays changed
  3. The object cannot be stretched
Show answer

It stays changed The object stays changed when the force is removed.

Check 6

Which of these is inelastic: a spring, plasticine or a stretched elastic band?

  1. A spring
  2. A stretched elastic band
  3. Plasticine
Show answer

Plasticine Plasticine, because it stays squashed.

Check 7

What is the equation linking force, spring constant and extension?

  1. force = spring constant × extension
  2. force = spring constant ÷ extension
  3. force = spring constant + extension
Show answer

force = spring constant × extension force = spring constant × extension (F = k × e).

Check 8

What is the unit of the spring constant?

  1. N
  2. N/m
  3. m/N
Show answer

N/m Newtons per metre, N/m.

Check 9

What does a large spring constant mean?

  1. The spring is soft
  2. The spring is long
  3. The spring is stiff
Show answer

The spring is stiff The spring is stiff and needs a large force to stretch it.

Check 10

In what unit must the extension be when k is in N/m?

  1. Metres
  2. Centimetres
  3. Millimetres
Show answer

Metres Metres.

Check 11

How do you change 5 cm into metres?

  1. Multiply by 100, which gives 500 m
  2. Divide by 100, which gives 0.05 m
  3. Divide by 10, which gives 0.5 m
Show answer

Divide by 100, which gives 0.05 m Divide by 100, so 5 cm = 0.05 m.

Check 12

A spring has a spring constant of 30 N/m. What force stretches it by 0.2 m?

  1. 150 N
  2. 30.2 N
  3. 6 N
Show answer

6 N 6 N, because 30 × 0.2 = 6.

Check 13

A force of 8 N stretches a spring with k = 40 N/m. What is the extension?

  1. 0.2 m
  2. 320 m
  3. 5 m
Show answer

0.2 m 0.2 m, because 8 ÷ 40 = 0.2.

Check 14

A force of 15 N stretches a spring by 0.3 m. What is k?

  1. 4.5 N/m
  2. 50 N/m
  3. 0.02 N/m
Show answer

50 N/m 50 N/m, because 15 ÷ 0.3 = 50.

Check 15

What does a straight line through the origin on a force-extension graph show?

  1. The spring has broken
  2. The spring is past its limit
  3. Force is proportional to extension
Show answer

Force is proportional to extension Force is directly proportional to extension.

Check 16

What does the gradient of the straight part of a force-extension graph represent?

  1. The spring constant
  2. The extension
  3. The energy stored
Show answer

The spring constant The spring constant.

Check 17

What is the limit of proportionality?

  1. The point where the spring breaks
  2. The point where force and extension stop being proportional
  3. The longest length of the spring
Show answer

The point where force and extension stop being proportional The point beyond which the extension is no longer proportional to the force.

Check 18

What does a curved force-extension graph show?

  1. The spring is stiffer
  2. The spring constant has doubled
  3. The spring is past its limit of proportionality
Show answer

The spring is past its limit of proportionality The spring is past its limit of proportionality.

Check 19

A spring is 15 cm long and its natural length is 10 cm. A student uses 15 cm as the extension. What is wrong?

  1. The extension should be 5 cm
  2. Nothing is wrong
  3. The extension should be 25 cm
Show answer

The extension should be 5 cm The extension is the increase in length, 15 − 10 = 5 cm.

Check 20

What is the equation for the energy stored in a spring?

  1. energy = spring constant × extension
  2. 0.5 × spring constant × extension squared
  3. energy = force × extension²
Show answer

0.5 × spring constant × extension squared energy stored = 0.5 × spring constant × extension² (Ee = ½ke²).

Check 21

The extension of a spring is doubled. What happens to the energy stored?

  1. It doubles
  2. It stays the same
  3. It becomes four times bigger
Show answer

It becomes four times bigger It becomes four times as big, because the extension is squared.

Check 22

Which store holds the energy in a stretched spring?

  1. The elastic potential store
  2. The thermal store
  3. The chemical store
Show answer

The elastic potential store The elastic potential store.

Check 23

Why does a steeper line on a force-extension graph show a stiffer spring?

  1. A steeper line means a longer spring
  2. The gradient is k, so steeper means bigger k
  3. A steeper line means less force
Show answer

The gradient is k, so steeper means bigger k The gradient is the spring constant, so a steeper line means a bigger k.

Check 24

A spring is stretched past its limit of proportionality and released. What may happen?

  1. It goes back exactly as before
  2. It gets shorter than before
  3. It may not go back to its original length
Show answer

It may not go back to its original length It may not return to its original length.

Check 25

What is the difference between a linear and a non-linear force-extension graph?

Show answer

A linear graph is a straight line through the origin. A non-linear graph curves.

Keep going with Forces and elasticity

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