Walking & Running

Legs as pendulums

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Walking is an inverted pendulum: the body vaults over each leg.
• Gravity limits walking to $v \le \sqrt{gL}$, about 3 m/s for adults.
• Running is bouncing on springy tendons.

Steps

1. An inverted pendulum
2. Vaulting over a stiff leg
3. Top walking speed
4. Short legs
5. Walking on the Moon
6. Legs as pendulums
7. Springs in your legs