Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Physics of bicycle helmet

  1. Jun 25, 2008 #1
    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. jcsd
  3. Jun 25, 2008 #2

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    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
  4. Jun 25, 2008 #3

    rcgldr

    User Avatar
    Homework Helper

    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.
     
  5. Jun 25, 2008 #4

    mgb_phys

    User Avatar
    Science Advisor
    Homework Helper

    Argghh, typo and now I can't edit it.
     
  6. Jun 25, 2008 #5

    berkeman

    User Avatar

    Staff: Mentor

    I fixed it for you. :biggrin:
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook