# Homework Help: Physics of bicycle helmet

1. Jun 25, 2008

### yahman

I am doing a lesson on Energy and Momentum and I am asked to write a report that includes sample calculations and examples, a thorough discussion of the principles of physics pertaining to energy and momentum, and apropriate diagrams and notations to demonstrate my understanding between the design and use of the helmet.

I am looking up google for information, and having some difficult time finding the right information, I appreciate if I could get some recommended links. I think they are asking me to demonstrate how kinetic energy is converted to potential energy during a crash but not quite sure how momentum is used (any help is appreciated) in the physics of helmets.

2. Jun 25, 2008

### mgb_phys

In a crash kinetic energy isn't converted to potential energy.
It is converted into the energy needed to deform and break the helmet (mechanical energy)
A more useful approach is accelearation. You know about f = ma?
The point of the helmet is to slow down the rate at which your head stops, by increasing the 't' in a = v / t, by taking time to deform it slows your head down more gently and so reduces the force.

Last edited by a moderator: Jun 25, 2008
3. Jun 25, 2008

### rcgldr

Make that increasing the time.

A helmet does two things: 1 - increases the distance of decleration, which increases the time of deceleration, which decreases the rate of decleration, which decreases the force. 2 - spreads the point of impact over a larger area.

4. Jun 25, 2008

### mgb_phys

Argghh, typo and now I can't edit it.

5. Jun 25, 2008

### Staff: Mentor

I fixed it for you.