Level 7: Lift and drag

Air and fluids · level 7 of 8 · rough age 15-16 (a guide for parents; anyone can start anywhere)

This level gives the two forces of flight their equations. You use the drag equation for cars, cyclists and falling skydivers, and see why a parachute alone cannot land a rover on Mars. Then the lift equation shows why aircraft on Mars must fly fast, and momentum theory gives the power Ingenuity needed to hover. Last come dust devils: spinning air with a low-pressure core.

Lesson	You will be able to
The drag equation	Use \(F_D = \tfrac12 \rho v^2 C_D A\), and the power needed against drag
Terminal velocity	Find the top speed of a falling object on Mars and on Earth
Landing on Mars	Explain how Perseverance shed its speed, and why it needed rockets
The lift equation	Use \(L = \tfrac12 \rho v^2 C_L A\) to find the speed a wing needs
How Ingenuity flew	Use momentum theory to find the power to hover
Dust devils	Explain how a dust devil spins up, and the pressure drop in its core

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