# Explain why the total mechanical energy of a skydiver falling through the atmosphere is not conserved, and describe the energy transformation that occurs as the skydiver reaches terminal velocity.

> IB DP Physics Standard Level (2023 syllabus) — A.3 Work, energy and power · Explain · 4 marks

> A skydiver jumps from a stationary helicopter and falls through the atmosphere. After some time, the skydiver reaches terminal velocity.

## Mark scheme (4 marks)

1. Air resistance (drag) acts on the skydiver, doing negative work on the skydiver / a non-conservative force acts on the skydiver
2. The work done by air resistance converts mechanical energy into thermal/internal energy (heat), so total mechanical energy decreases
3. At terminal velocity the net force on the skydiver is zero, so the drag force equals the weight / gravitational force
4. At terminal velocity, the loss in gravitational potential energy per unit time equals the rate at which energy is dissipated as thermal energy (the kinetic energy remains constant)

## Key terms

- [mechanical energy](https://www.gradenine.co.uk/glossary/mechanical-energy)
- [terminal velocity](https://www.gradenine.co.uk/glossary/terminal-velocity)

## Related

- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](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/explain-why-the-total-mechanical-energy-ad0f4da6) · Published by Druglandscape Ltd.