# Soccer balls

## Question:

I am helping some students who want to do a project involving the physics of kicking various kinds of soccer balls (They are 10 -11 years old). I wanted to help them formulate a hypothesis and find other experiments along that line that might help in their project.

1. Kicking or throwing is a really difficult thing to measure because the force involved in the muscles is so hard to determine. There is an experiement that we do here that could measure that but it involves momentum and would probably be much too hard for 10 -11 year olds. Anyway I will describe it below and you could maybe modify it if you think it is worth it.

2. Kicking a football
You could modify the classic experiment to find the force needed to kick a football. Simply kick the ball and find out how far it goes – the bigger the kicking force the further the ball will go.

3. General projectiles
Try using rubber bands to simulate muscles and get them to measure the range of various projectiles. You can vary the mass of the projectile, the angle of projection (by firing the projectile up a ramp) and the force needed (simply by investigating the properties of the rubber band). Look up the Roman siege engines used in Europe around the year 30 AD. Direction is very important – you can kick a ball really hard but if it is just going horizontally it won't get far before it touches the ground.

4. Discuss the effects of air on the path of the ball. Compare it with golf balls. Why ere there dimples in a golf ball – it makes them go further. Balls swerving in the air – what we call a banana shot. Try kicking balloons – they are much lighter than a soccer ball but won't get far.

5. Principle of impulse – the longer your foot is in contact with the ball the further it will go. Try kicking balls when standing at different places relative to the ball.

6. Properties of your body that affect how far you can kick. It is not always possible to give it the biggest "boot" by applying the principles of Physics alone!

7. There are a number of very good CDs that show slow motion clips of jumping, throwing and collisions. A very good one available in the UK is called Multimedia Motion. Aimed at older students there are some really good clips. Your children might find it useful with help.

8. Use a plastic tube as a blowpipe to project marbles at varying angles (N.B you need to fit a metal rod across the end nearest your childrens' mouths to stop them swallowing the marble!

9. You could arrange a competition between the children to see who can kick a ball the furthest. From the ground or dropped from their hands.

10. Could you video their attempts and analyse what they do?

11. How about going to a local soccer match or indeed watching matches on a video to look at how far football players can kick them.

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