Blow-and-Go Parachute
Students make a skydiver and parachute contraption to demonstrate how drag caused by air resistance slows the descent of skydivers as they travel back to Earth. Gravity pulls the skydiver toward the Earth, while the air trapped by the parachute provides an upward resisting force (drag) on the skydiver.
Drag slows down a skydiver's descent.Copyright Wikimedia Commons http://commons.wikimedia.org/wiki/File:Skydiver_-_AirExpo_Muret_2007_0240_2007-05-12.jpg
To design safe recreation and transportation vehicles, engineers take into account all forces acting on the object. Sometimes they use the drag force to slow down or control a moving object, for example, in designing a parachute, vehicle brakes or paper moving through a copy machine. Engineers modify their designs to make the forces of thrust, lift, weight and drag smaller or larger, which changes how the object behaves when moving through air or water.
Launching the parachutes; how they fall.Copyright Hauser, Jill Frankel. Gizmos and Gadgets: Creating Science Contraptions that Work (and Knowing Why). Charlotte, VT: Williamson Publishing, 1999.After this activity, students should be able to:
- Describe which forces act on the skydiver as they are going up in the air and coming back down to the ground.
- Experimentally identify which geometric shapes most successfully reduce drag.
- Collect data from the experiment and interpret results.
- Characterize an engineer's need to identify the interactions between forces.