Science projects need some forces to act. Any working model will need some energy to make it go. This can be electrical energy provided by a wire and a plug, or mechanical energy provided by physical action being repeated or kinetic energy borrowed from a moving object.

What is gravity? It is the pull of the earth on all things that are on its surface. Everything experiences gravity, from your glass of water to the ball you play tennis with. That is why no matter how high you throw some thing it is still bound to come down again. That is the force that is always available to you no matter where you stand on earth.

So why not harness this power and make a science project . You may want to explain why a pencil will fall to the earth if dropped point facing down, but balances on your finger when you put it mid way lying down. Although it would be possible to do more complex experiments as well. A waterfall using a pump would seem like a good idea.

If you are not interested in getting wet, try out this experiment here. It may be more to your taste. All that matters is that you try and harness this ever present force of the earth in your science project. You can come up with a way to test the acceleration of different objects of different weights due to gravity as well.

Try using a video camera with your parent and calculating the time it takes for a feather, a coin, a ball and a bottle of water to fall to the ground. The end results may surprise you.