# A student wants to estimate the time it takes for a human heart to beat once. Explain how the student could arrive at a reasonable estimate, including a final value with appropriate units.

> AQA A-Level Physics (7408) — 3.1.3 Estimation of Physical Quantities · Explain · 5 marks

## Mark scheme (5 marks)

1. Method: count the number of heartbeats (pulse beats) in a known time interval (e.g. 60 seconds / 1 minute)
2. Uses a timer / clock / watch to measure the time interval accurately
3. Divides the time interval by the number of beats to find the time per beat (correct method for calculating period from rate)
4. States a reasonable value for resting heart rate used in the calculation, e.g. approximately 60–80 beats per minute
5. Gives a final estimate of approximately 0.75–1 second per beat with correct unit (seconds)

## Key terms

- [units](https://www.gradenine.co.uk/glossary/units)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-wants-to-estimate-the-f7f061d5) · Published by Druglandscape Ltd.