Technology

Gilla:		Dela:

Materials

• 1 plastic bag
• 1 pen
• 1 ruler
• 1 paperclip
• String (thin)

Short explanation

A parachute works by creating as much air resistance as possible and thus slowly lowering an object through the atmosphere.

Long explanation

When a parachute falls through the atmosphere, its underside collects lots of air. Within a small volume, lots of air molecules gather, which collide with each other and what is around them. These collisions are the same as air pressure, and the air underneath the parachute therefore pushes on what is around it. It therefore pushes the parachute upwards and partially counteracts the gravitational pull of Earth on what is hanging in the parachute. This push is called air resistance or drag.

A round parachute ususally has a hole in the middle. This may seem illogical because the air resistance then decreases. But that hole is an important detail. That is because there is a limit to how much air can be collected underneath the parachute and when that limit is reached, the air must go somewhere. If there is no hole in the parachute, the air spills over one of the sides of the parachute. The parachute is flipped inside out on that side and its air-collecting bulging shape is lost. If instead there is a hole in the middle of the parachute, the air can escape through it and the parachute will keep its shape.

Test and improve

You have now built your first prototype. There are probably improvements to be made. In order to keep working on your design, try answering any of the following questions.

• What happens if you make a larger or smaller parachute?
• What happens if you change the shape of the parachute?
• What happens if you hang a heavier or lighter object in the parachute?
• What happens if you make a hole in the middle of the parachute?

Gilla:		Dela: