Spin It!

Have you ever wondered why some things are easier to spin than others?

There are actually several ways to explain the motion of spinning, but they can all be summed up by Newton’s First Law of Motion that says an object in motion will remain in motion and anything that is still (at rest) will stay still until another force interferes with that object.

EXAMPLE: If you stand a penny on its edge and begin to spin it, it will keep spinning until a) you knock (force) it to fall or b) the gravity forcing the penny to go around and around decreases to nothing.

NOTE: As the gravity decreases the friction between the penny and the air increases and eventually the air is able to put enough force on the penny to knock it down.

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How the state matter affects spinning

The state of matter also affects how something spins. Here’s why…

  • Liquids rotate slower than solids do. This is because liquids (and gases) don’t have a definite shape. The molecules in a liquid or gas move around at will. Not all of them move at the same time or in the same direction.
  • Solids have a definite shape. This means all the molecules in a piece of solid matter move in the same direction at the same time.

Because of the molecules of solid work as a team, the solid piece of matter spins or rotates better than a liquid or a gas.

What does this have to do with how things spin?

Let’s find out!

Here is what you need:

  • Stove
  • Saucepan
  • Two eggs
  • Tabletop

Here is what you do

  • With the help of an adult, bring a pan of water containing one of the eggs to a boil
  • Boil the egg for three minutes and turn off the stove
  • Carefully pour the water out of the pan and let the egg set until it is cool enough to handle
  • Once the egg is cool enough to handle, set the hardboiled egg and the raw egg in the center of a table.
  • Spin the raw egg by standing it upright with the smallest tip on the table. Count how many seconds it spins before falling down.
  • Do the same with the hardboiled egg.
  • What are the differences between how the two eggs spin? Which egg spins longer? Which egg stands up straighter?

Since you can’t see inside the egg:

You can’t see what happens when you spin a liquid and a solid, but you can’t see why it happens—at least not inside the egg. But by doing the following experiment, you will be able to see what is happening inside the egg.

  • Clip two pieces of paper to a fence.
  • Standing 5 to 6 feet from the paper, throw a rock at one piece of paper.
  • At that same distance, throw 1 cup of water at the other piece of paper.

NOTE: Don’t throw the cup—just the water inside it.

Notice this: the entire rock hit the paper (if you didn’t miss, that is). The rock did not break apart through the air. The water, however, did spread out once it left the confinement of the cup. Not all of the water hit the paper because it was trying to take on the shape of the space it was in.

Try this: