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AQA · GCSE · Combined Science · Higher

Kangaroo speed and jump height

Q07.1 3 marks

Kangaroos are large animals that travel by jumping. Figure 8 shows a kangaroo. Each leg of a kangaroo has a tendon connected to a muscle. Each tendon can be modelled as a spring. When a jumping kangaroo lands on the ground, the tendons stretch. Figure 9 shows a sketch graph of how the maximum tendon length during a jump changes with the speed of the kangaroo.

Sketch graph with speed of kangaroo on the horizontal axis and maximum tendon length on the vertical axis. The line slopes upward, showing maximum tendon length increases as speed increases.

Figure 9

Enlarged question image

Sketch graph with speed of kangaroo on the horizontal axis and maximum tendon length on the vertical axis. The line slopes upward, showing maximum tendon length increases as speed increases.
Figure 9
Photograph of a kangaroo in mid-jump.

Figure 8

Enlarged question image

Photograph of a kangaroo in mid-jump.
Figure 8

Explain why a kangaroo can jump higher as its speed increases.

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Marking points

  1. 1 Use the graph to state that the tendon extension or stretch increases as speed increases.
  2. 2 Explain that a larger extension means more elastic potential energy is stored in the tendon.
  3. 3 Explain that this elastic potential energy is transferred to gravitational potential energy, allowing the kangaroo to jump higher.

Full-mark answer

As the kangaroo’s speed increases, the maximum tendon extension increases. A greater extension means more elastic potential energy is stored in the tendons. This energy is then transferred to gravitational potential energy, so the kangaroo can jump higher.

Why this answer loses marks

The tendon gets longer so it jumps higher.

This uses the graph but does not explain the energy storage and transfer.

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