1 · IGCSE Physics
Skydiver and terminal velocity
Watch how weight and air resistance change the resultant force on a falling skydiver, and see the velocity–time graph level off at two different terminal velocities before and after the parachute opens.
W = mg (g = 9.8 m s⁻²)
Air resistance D = kv²
Resultant F = W − D, a = F / m
Terminal: kv² = mg → v = √(mg / k)
Air resistance D = kv²
Resultant F = W − D, a = F / m
Terminal: kv² = mg → v = √(mg / k)
Time tVelocity vWeight WAir resistance DResultant FAcceleration aTerminal v₁Terminal v₂Stage
Try this
- Press Play and wait until the graph is flat before opening the parachute. Check the free-fall terminal velocity against √(mg/k₁).
- Raise the mass from 80 kg to 120 kg. Predict by what factor both terminal velocities increase (hint: √1.5), then test it.
- Open the parachute early, before v₁ is reached. Watch the direction of the resultant arrow while the skydiver slows down.
Common error: saying the skydiver goes upward when the parachute opens — the resultant force is upward, so the skydiver decelerates while still moving downward.