Spinning Things

A lot of things spin – bike wheels, footballs, hard disks in your computer, and even the Earth – they’re all twirling around. Spinning things have inertia, which means they keep spinning unless something slows them down. Bike tires keep spinning until you put on the brakes. A football spirals through the air until you catch it. The Earth keeps on spinning 24 hours a day, seven days a week. It’s been spinning for over four billion years.

You can feel the force of spinning bike tires when you put on the brakes – if you’re going really fast, you have to push really hard to stop yourself. The more massive a spinning thing is, the harder it is to stop it, and fast spinning things are harder to stop than slow spinning things. A flying disk flies and curves because of it’s spin. Skip it on it’s side and it’s front edge goes up. When you push on a spinning thing, it pushes back. It’s wild!

Bill Nye the Science Guy will make your head spin – with science!

The Big Ideas

• A spinning thing will keep spinning unless something slows it down.
• When you push on a spinning thing, it will push back.

Did You Know That?

• A typical car tire spins 27 million times a year?
• Dave Spathalky set a record on October 21, 1986, when he spun 84 plates at the same time?
• The speed of the Earth’s spin measured at the equator is 1,673 kilometers (1,040 miles) per hour?

Books of Science!

• “Tops and Gyroscopes” by R. W. Campbell. Published by Thomas Y. Crowell Company, 1995.