Free Fall and Air Resistance (Terminal Velocity)

Theory

Without air, every body falls with the same acceleration $g$, regardless of mass: $y=y_0-\frac{1}{2}g{t}^2$. With air, drag $F_D=\frac{1}{2}\rho C_{d}A{v}^2$ grows with speed until it balances the weight: the terminal velocity is $v_t=\sqrt{\frac{2mg}{\rho C_{d}A}}$.

What to observe

• The iron ball lands first; the balloon almost floats.
• In the graph, the balloon’s speed stops growing: it reached $v_t$.

Try this

• Click on empty space and turn off Air resistance: they all land together!
• Switch gravity to the Moon’s value.

Also available in: Queda livre e resistência do ar (velocidade terminal) (Português) · Caída libre y resistencia del aire (velocidad terminal) (Español)