# What are some examples of Charles' law?

Jun 27, 2014

The physical law that the volume of a fixed mass of gas held at a constant pressure varies directly with the absolute temperature.

Doubling the temperature of a gas doubles its volume, as long as the pressure of the gas and the amount of gas isn't changed.

Helium Balloon on a Cold Day

If you have bought a helium balloon for your brother or sister you may have noticed this phenomenon. If it's cold outside, your sibling's face may fall when he/ she notices that the helium balloon has crumpled. All isn't lost, of course, because once you enter your warm home, the balloon returns to its original shape. This is because, according to Charles' law, a gas takes up more space when it is warm.
At low temperature the gas molecules inside the balloon , slows down and takes up lesser space, and the balloon looks crumpled.
When you leave that balloon in a warm room or warm place the molecules of gas inside the balloon speeds up, spread out and takes up more space and balloon becomes bigger.

Tire Pressure

Typical manufacturers recommend that automobile tire pressures vary between around 25 to 35 pounds per square inch. But if you read your owner's manual carefully, it will mention that tire pressure should always be measured cold. That's because driving around heats up tires. Charles' law states that the gas should occupy more space when heated, but a tire does not expand very much. This causes the tire pressure to be higher when warm. Consequently, measuring tire pressure when the tire is warm will give you the false impression that you have filled your tires with too much air.

The Dented Ping Pong Ball

If you are into ping-pong, also called table tennis, a dented ping pong ball is something you have probably encountered. Rather than discard it, you can restore it by placing it into a saucepan half filled with water. Apply gentle heat to the saucepan, stirring constantly. If the ball is not cracked by the dent, the air inside will expand as it heats, pushing out the dent and restoring the ball to its original shape.