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

Help needed for a force calculation

Tags:
  1. May 8, 2015 #1
    Hello,

    I need to calculate the impact that a car (small car) has on a metal structure.

    What I know:
    The mass of the car : 99 kg, the velocity of the car : max 3 km / h -> 0,833333 m / s
    Thus the force of the car at 3 km / h is 82,5 newton.

    Now I need to know how much that metal structure can receive as impact.
    The structure is made of steel tubes with keyclamps. The tubes have a diameter of 42,4 mm and they weights 2.57 kg / m.
    The thing is that the structure is fasten in the ground with screws :p what doesn't make it easier to calculate I guess.

    I know it's a long shot, but if somebody could help me out how I can try to find something out to give a result ?
    The thing is I have learned all of these at high school but it's too long ago and can't remember :(

    Thanks for your help.

    Regards from Belgium
     
  2. jcsd
  3. May 8, 2015 #2

    jbriggs444

    User Avatar
    Science Advisor

    Sorry, that result is not even dimensionally correct. The product of mass and velocity has units of kilogram meters per second. That is a unit of momentum. The Newton has units of kilogram meters per second squared. It is a unit of force.

    However, you have another problem. Force, momentum, energy... None of them is a single magical number that equates to how much damage an impact will cause or how much a structure can absorb without permanent damage (though energy comes close). Collisions are complicated. Real world experience and experiment trumps high school physics calculations every time.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Help needed for a force calculation
Loading...