Experiment - Air Resistance

In Adventures in Skydiving [1] Philippe Theys says

"Who would be crazy enough to leave a perfectly good airplane, accelerate for eleven seconds to reach a terminal velocity, where the pull of gravity equals wind resistance, of almost 200 kilometers per hour (125 miles per hour)?"

As we learn in the article, many people do - and love it! At terminal velocity, of course, these jumpers open a parachute and float to the ground. Once the parachute is opened, velocity is reduced to only 6 meters per second, or about 22 kph -- slow enough to land safely. The total mass of Philippe + parachute is the same, but with the parachute spread above him rather then folded up tightly in his back pack, the air resistance is much greater.

Here's a little experiment that demonstrates how this works.

Materials

Two pieces of paper, the same size
Cellophane tape

The Experiment

Fold one piece of paper in half
Fold it in half again. The second fold should be at a 90° angle to the first fold.
Rotate the paper 90° and again fold it in half.
Continue to fold the paper in half until you can't make another fold. Tape it tightly together with cellophane tape so that it does not unfold.
Put a piece of cellophane tape on the second piece of paper. It should be the same length as the piece of tape you used on the first piece of paper. This tape doesn't hold anything. It's just there so that the two pieces of paper end up with exactly the same mass.
Loosely crumple the second piece of paper.

What do you expect to happen when you drop both pieces of paper from the same height?

Course:

Science [5]

Result/Solution(s)

The drop We dropped both pieces of paper at the same time. The tightly folded one hit the floor first.

How this works

When an object is dropped, the force of gravity will cause it to speed up as it falls. But friction with the air, called drag, will tend to cause it to slow down. How much drag there is depends mostly on two factors:

Speed: The faster an object moves through air the more drag there is.
Shape: A compact object experiences less drag than an object of the same mass that is spread out.

As a falling object speeds up, drag increases until it is equal to gravity. At that point, the object continues to fall at a constant speed, called terminal velocity. The tightly folded piece of paper experiences less drag than the loosely crumpled piece. The balance between gravity and drag occurs at a lower speed, a lower terminal velocity, for the crumpled paper.

Take loosely crumpled paper and crumple it a bit more tightly. How does this affect the speed with which it falls?

Air and space experiment [6]

ps_nid:

20128