Science Experiments

How fat would you have to be to stop a bullet?

Sun, 17th Jun 2007

Listen Now    Download as mp3 Part 1,2 from the show Forensic Science

What you Need

We went to the Cavendish Laboratory to discover how fat you would have to be to stop a bullet.  We used a gas gun,  which is basically a huge air rifle.  There is a chamber that is filled with high pressure helium (this is used because it is lighter than air so will expand more quickly).

The gun has a 3m long barrel which you load a small ball bearing into.  There is a valve between the chamber and the barrel which can be opened very quickly.  The gas (at about 70 atmospheres) then expands extremely rapidly forcing the bullet out of the barrel at supersonic speeds.


The gas chamber

The bullet

The gas chamber which is filled by high pressure helium

The bullet  - a small steel ball bearing.

A perspex tube was filled with gelatin, which is a similar density to fat, to act as the target.


The tube of Gelatin


The perspex tube full of gelatin to act as a target

This was mounted in front of a backstop full of rags.



What to do

What may happen

A bullet hitting Gelatin


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