# A passenger jet accelerates from rest along a runway and reaches a take-off speed of 80 m/s in 40 seconds. After take-off, the jet climbs at a constant speed but changes direction as it follows a curved flight path. Explain why the jet has a changing velocity during the climb even though its speed remains constant. Then describe what the term 'acceleration' tells us about the jet during its take-off run along the runway.

> Eduqas GCSE Physics — 4.1 Speed, velocity and acceleration · Explain and Describe · 4 marks

## Mark scheme (4 marks)

1. Velocity is a vector quantity / velocity has both magnitude (speed) and direction
2. Because the direction of travel changes (on the curved path), the velocity changes even though the speed stays the same
3. Acceleration is the rate of change of velocity
4. During the take-off run the jet's velocity is increasing (from 0 to 80 m/s) so it is accelerating / the jet has a positive acceleration

## Key terms

- [velocity](https://www.gradenine.co.uk/glossary/velocity)
- [speed](https://www.gradenine.co.uk/glossary/speed)
- [acceleration](https://www.gradenine.co.uk/glossary/acceleration)

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "Explain and Describe" 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-passenger-jet-accelerates-from-rest-2d60d11a) · Published by Druglandscape Ltd.