## Butter Guns and Inverse Square Laws

Posted in A2 Unit 5: Radioactivity, AQA A2 Unit 5 by Mr A on 18 Jan 2010

A butter gun was designed by a restaurant in order to butter pieces of bread very quickly. Charged with one knob of butter (its maximum capacity, which it fired every time) it could butter one piece of bread effectively at a distance of 1 foot.

However, one day someone discovered that if the gun was fired from 2 feet instead, it could butter four pieces of bread. The restaurant manager was very excited, as this meant his staff were that much more efficient.

Whatsmore, it was discovered that if the gun was fired from 3 feet, it could cover an impressive nine pieces of bread. Needless to say, the manager was pleased. However, the customers soon started complaining.

Why were the customers complaining?

If one knob of butter gets on one piece of bread from 1 foot away, how much is on each piece of bread at 2 feet?

How much is on each piece of bread at 3 feet?

Can you see the pattern; how many pieces of bread could be covered at 7 feet, and how much butter would be on each piece of bread?