WATER THAT DEFIES GRAVITY!

You Will Need:

• An empty bucket - (it must have a good strong handle)

• Water

• Lots of room - (preferably outdoors)

PREPARATION

Start by filling the bucket about 1/3 (one third) of the way up with tap water.  You might want to use cold water, in case you spill it on yourself.

You might want to go outside so that you don't make mom nervous.  She wouldn't like it if you spilled water on the living room carpet, sofa, ceiling, and drapes.  Find a place where you can swing your arms around without coming close to hitting anything.

DOING THE EXPERIMENT

Holding the bucket by the handle, start swinging it back and forth, like a pendulum, or playground swing.  Continue to swing in higher and higher arcs.  When you get it going good, continue your swing into a full circle, with the bucket going over your head.  Look to see what happens to the water!

If you got it swinging fast enough, the water should have stayed in the bucket, without one single drop spilling out.  Now you can tell your friends that you have water that defies gravity.

EXPLAINING HOW IT WORKS

Although gravity is trying to pull the water down to the ground, there is another force at work, keeping the water from spilling.  This force is mentioned in Newton's first law:

Notice the second part of Newton's first law.  The bucket you are swinging is an object in motion.  The water inside the bucket is another object in motion.  

As the bucket goes around in the circle, it is trying to go in a straight line.  Your hand is preventing it from doing this, and instead, making it go in a circle.  If you let go of the handle, the bucket would then go in a straight line (called a tangent).  Since you can think of a circle as a bunch of straight lines, this straight line would be an extension of the last straight direction the bucket was moving.  We call this pulling of the bucket outward in the circle centrifugal force.  

The water in the bucket is also trying to go in a straight line.  However, the bottom of the bucket prevents it from traveling in the straight line.  No matter what part of the circle the bucket and water are in, the water is still trying to travel in a straight line through the bottom of the bucket.  

When the bucket is upside down, the force of gravity is trying to pull the water down to the ground.  However, the centrifugal force is stronger than the gravity force, and prevents the gravity from affecting the water.  That's why the water stays in the bucket, instead of coming out on your head.  Unfortunately, if you stop the bucket from moving, gravity would take over, and pull the water down to the ground (or you, whichever it finds first).

Many amusement park rides work on this principle.  Have you ever gone on one of those roller coasters that go upside down?  Well, if you had your eyes closed, you could never tell that you went upside down.  Your body feels the centrifugal force pulling you down into the seat, just like the water was pulled down into the bucket.  Therefore, you never feel a sense of being upside down.