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Soccer by Dana and Alicia

We get our kicks playing soccer! We're strong players, but Dana wants to figure out how to really boot the ball the length of the field. Our question? If your legs are bigger, can you always kick the ball farther?

What did we do?
We built a kicking machine to test different sized legs in a soccer kick. With a spring acting as the leg's "muscle," we added attachments that made the mass of the leg two and three times heavier. We tested each "leg" three times - the light leg, the medium leg and the heavy leg - to see how far it kicked the ball. Strangely enough, we found out the lightest leg kicked the ball farther every time. We found out that the heavy leg wasn't swinging as fast as the light leg. So, we added a second spring to give the heavier leg more speed. With one spring on the light leg, the ball flew an average of 47 feet. With one spring on the heavier leg, it only flew 27 feet. When we added the second spring, the heaviest leg sent the ball sailing to 55 feet!

What did we find out?
Just having a big leg doesn't send the ball soaring. It's a combination of leg mass AND speed that gives the most effective kick. If we want to improve our soccer kicks, there are two things we can try. We can build up our leg muscles and then we can use that added muscle to swing our legs faster.

What can you do?
• Air pressure inside a ball changes the way it bounces. Design an investigation to show this influence. Get an air pump with a pressure gauge on it so you know how much air is in the ball. Measure how the ball bounces when you drop it from a certain height. Ask a friend to dribble the ball and get their feedback on how the ball performs at different pressures. Is more air pressure better?

• How do you choose the right baseball bat for you? Design an investigation where you and a friend test different bats. You can measure how far the ball flies when hit with different sized bats or see how accurately the batter hits a ball with different bats.

• Use this sports physics investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!

 SciLinks More on Sports & Conditioning Go to the DFTV Boards, and tell us about your science investigation.