Classroom Activity for 11-14
What the Activity is for
Parachutes provide greater frictional forces.
This activity introduces the idea that objects do not continue to fall faster and faster but reach a final constant speed (or terminal speed). The size of the final speed depends on the frictional forces acting (with a big open parachute the final constant speed is much lower than for free-fall of the same object or person). Furthermore, a final constant speed is an indicator of zero resultant force.
What to Prepare
- toy plastic figures with parachutes (can be bought or made)
What Happens During this Activity
Use two identical figures – one with a parachute strapped to their back, the other with their parachute open and untangled. Drop the two figures from the same height at the same time and see which one hits the ground first.
Discuss result with the class. The downward force acting on both figures is the same – the same force of gravity acts on both. Why do they not reach the ground at the same time? Because the upward force acting on the two figures is not the same. The open parachute provides a greater frictional force upwards, which means that the figure with the open parachute reaches their constant
terminal speed before the other one.
The figure with the open parachute therefore takes a longer time to reach the ground and lands safely. The figure with the closed parachute would also reach a terminal speed if allowed to fall a great height but would first need to speed up until the force of the wind, or air resistance, was strong enough to balance the force of gravity pulling down.