Explore: Parachute Plunge

Using buoyancy is one way to counteract gravity. You saw how hot air balloons were able to do this. Parachutes must also counteract gravity to some degree. An object that is falling is being pulled downwards by the force of gravity. A parachute can be used to slow this fall.

Parachutes work by producing drag. Usually, flying objects try to reduce drag to move more easily through the air. In this case, a parachute is used to increase drag, by increasing the amount of air resistance acting on the object. Drag acts directly against gravity by pulling upwards, the result is that the object falls slower. The more drag a parachute produces, the slower it will fall.

Remember that drag is affected by the shape of an object and how smooth or rough it is.

Which umbrella will have more drag on a windy day?

The open umbrella has more drag because it is more difficult for air to move past it. Narrow, smooth, and more streamlined objects have less drag than wider, rougher objects. Keep this in mind as you design your own parachute.

Your parachute will have three basic parts:

• Canopy: the part that opens up to produce drag
• Strings: that attach the canopy to the load
• Load: the weighted object that is being dropped

To make this a fair test, you will need to keep everything about your parachute the same except for the one thing you decide to test for.  This is your manipulated variable.  You could decide to change one of the following:

• material of your canopy
• size or shape of your canopy
• type or length of strings
• size, mass, or shape of your load

Remember that you are testing to see which of your changes causes your parachute to stay up longer.  Therefore, choose a manipulated variable that you think will be most effective in helping you achieve this goal
When making your hypothesis and design, consider which will fall faster:

• A heavier load or a lighter one?
• A larger canopy or a smaller one?
• A canopy made with thick or thinner material?

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