Things spin around us, under us and above us every day.
When something is spinning, it means that it is turning or rotating quickly around an axis (point). That point is usually in the center, but it does not have to be. Many factors affect how an object spins, including size, shape and distribution of mass.
Before you can experiment with spin, there are a few things you need to know about spinning objects: A spinning or rotating object has energy, just like any moving object. The energy related to the spinning is called rotational energy. An object with more rotational energy spins faster.
The force that keeps objects moving in a circular path is called centripetal force. If you tie a string to an empty can and swing that can above your head, the string provides centripetal force, which keeps the can moving in a circle. If you let go of the string, the can will fly off in a straight line.
Centripetal force is what keeps a moving car in a curved path as it rounds a corner.
Without centripetal force, the car would skid off the road. Centripetal force is also at work in your washing machine. The spinning washer exerts centripetal force on the clothes in the washer. But because there are small holes in the washer, the water is able to escape that force. This separates the clothes from the water.
Now that your head is spinning from so much science, it’s time to try your own rotating experiments.
Experiment 1: Spiral Vortex
Supplies:
Printer paper
Scissors
String
Tape
Cut out a spiral pattern on paper. Make it as big or small as you want.
Tape a two-foot string to the center.
Hold the string and gently pull the spiral behind you. What do you notice?
What’s going on? Moving air pushes against the arms of the spiral shape, causing it to spin. The energy of the moving air is converted into rotational energy. Faster-moving air has more energy and will cause the spiral to spin more quickly.
Experiment 2: Waiter Tray
Supplies:
2 large craft sticks
1 small paper plate
String
Tape
Ball of clay
Tape the craft sticks into an X shape.
Tie a two-foot string to the end of each leg of the X.
Tape a paper plate onto the middle of the X.
Hold the strings above the plate so they are taut and tie them all together.
Place the ball of clay on the paper plate and swing the plate in a circle in front of you so it moves like a Ferris wheel. (Do this outside so you don’t break anything.)
What’s going on? As you spin the plate, centripetal force keeps the plate moving in a circle. That force can be stronger than gravity. Centripetal force also keeps the clay moving and prevents it from falling off the plate. So even when the plate is upside down, the clay does not come off the plate.
Extension: Try using a paper cup of water on the plate instead of the ball of clay. What happens?
Want to experiment more with spinning objects? Come see “Spin: The Science of Rotation,” the newest traveling exhibit at Discovery Center Museum. This exhibit that explores the fun and science of objects that rotate. Using interactive exhibits and real-life examples, visitors can explore how objects spin, why things spin at different speeds and how we use spinning objects in our daily lives. For more information visit discoverycentermuseum.org or call 815-963-6769.
Jacquelynn Accetta is an educational specialist at Discovery Center Museum. She enjoys trying to see how long her bike wheels will keep spinning (before she has to pedal again!) as she rides down a hill!
