Forces Experiments
Gravity and Air
Teacher had a hair dryer and some balls of different weights and sizes.
After chatting about what the balls were made of, and what the balls are filled with, we put the balls in order, starting with the heaviest and finishing with the lightest.
The bouncy rubber ball was heaviest, the ping pong ball was next and the polystyrene ball was the lightest.
Next, we watched what happens when we let go of a ball:- each one falls to the ground because gravity is acting on it.
We took out the hairdryer, and guessed first what would happen if we put each ball into the slipstream and let the force (air) act on it.
We got so good at this that we could even manage to balance two balls in the slipstream.
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| A rubber bouncy ball does not float at all! |
A little polystyrene ball will float up in the air stream, but is not heavy enough, or have a strong enough gravitational force to stay in the slipstream. It just bounces away, every time.
So, what happens if we use a cardboard cylinder (a toilet roll or a kitchen roll) to make sure all the air travels upwards and not to the side.
The ping pong ball is pushed up much higher.
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