A comparison on the ability of different brands of bicycle helmets to absorb shock
The experimental data and analyzed results do not support the hypothesis that a more expensive bicycle helmet will reduce the force of impact on a cyclist's head during a collision.
Bicycle helmets are available in many sizes for children, teenagers and adults, and have to be worn correctly to minimize the risk of injuries to the cyclist. Helmets have to be fixed on to the head using the straps provided, and adjusted accordingly to ensure a proper fit.
Try to repeat the science fair project by increasing the height from which the weight was dropped, and try using heavier weights. Perhaps your results will be different? After all, a rider typically weights much more than 3kg. Also, repeat the experiment with different brands and models of helmet.
Bicycle helmet - http://en.wikipedia.org/wiki/Bicycle_helmet
Bicycle helmet types - http://www.bhsi.org/types.htm
Caution should be taken to prevent the falling weight from hitting anyone