1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

It's a pretty simple question but it's been racking my brain. Say I

  1. Jul 21, 2010 #1
    It's a pretty simple question but it's been racking my brain. Say I wanted to build a shock-proof computer case, would I want it to be heavy or light? My though is that it should be heavy.

    If I kicked a 1Kg case with 1000 newtons of force the case and components would accelerate are 1000m/s^2

    If I kicked a 1000Kg case with the same 1000 newtons of force the case and components would accelerate at 1m/s^2

    So am I correct in saying that the case should be heavy?
  2. jcsd
  3. Jul 22, 2010 #2
    Re: Shock

    Your analysis is correct.

    The best sort of shock-absorbing case for anything is a really heavy one, with the protected items held inside by shock-absorbing, flexible material.
  4. Jul 22, 2010 #3
    Re: Shock

    Ok thanks for the help but one more hypothetical

    If you dropped the cases from equal distances, all/most the force would be transferred to the ground and not the computer components since they would accelerate and decelerate at the same rate (gravity)
    Last edited: Jul 22, 2010
  5. Jul 22, 2010 #4
    Re: Shock


    You have to think of it like this:-
    If you drop an object it will always fall at the same speed, you can't do anything about that.
    When it hits the ground it suffers damaging forces because it is decelerated suddenly (and F=ma).
    All you can do it to reduce the deceleration somehow. And the only way to do that is to give it room to decelerate more slowly. By suspending it inside a case with cushioning, the moment the case touches the ground the cushioning applies a gentle force to the object, slowing it - hopefully it will be slowed gently to zero before it hits the side of the case.
  6. Jul 22, 2010 #5
    Re: Shock

    OK say the cases are exactly the same in every single way, except the mass

    The force of the 1000Kg case hitting the ground (10,000N) would be much greater than the force of the 1Kg case hitting the ground (10N). But would the force being exerted on the computer components be the same since they would have the same mass?
  7. Jul 22, 2010 #6
    Re: Shock

    And that would suggest there's no advantage to a heavy case?
    But being dropped is not the only accident that can happen.
  8. Jul 22, 2010 #7
    Re: Shock

    Exactly, I don't see myself lifting, much less dropping a 1000Kg case, hehe. It would be much more likely to be kicked or knocked over.

    Thanks for the confirmation of my thoughts
  9. Jul 22, 2010 #8


    User Avatar
    Science Advisor

    Re: Shock

    Yeah, if you drop it, the mass cancels out from all considerations. But in all other situations it does help to have a heavy case.

    The perfect solution would probably be a light case to which everything is attached inside a heavy case with shock-absorbent material in between.
  10. Jul 22, 2010 #9
    Re: Shock

    Does newtons third law come into play? The case exerts a force of 10,000N on the ground and the ground exerts -10,000N on the case, but does that ever matter(considering force normal)?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook