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I Force exerted on chain

  1. Oct 5, 2016 #1
    I want to know. If you have a car that weighs 4 thousand pounds, and it is moving at 60 mph with a chain on it. What would be the amount of force applied to the chain when the chain reaches its maximum length. This is ignoring the fact that the car would rip apart when the chain stops. This is just an example.
     
  2. jcsd
  3. Oct 6, 2016 #2
    Hello my Friend,

    It is an Interesting problem!
    Can you elaborate the situation?
    Is the chain touching Ground or Hanging between its Source joint and Car?? and When car moves, should I take Friction of ground on chain into account?
     
  4. Oct 6, 2016 #3
    Sorry if i was not clear. I am not counting the friction and everything else. I am just saying a chain to have a hypothetical object that will stop a heavy object in its tracks. Just as an example to get a simple equation for a sudden stop.
     
  5. Oct 6, 2016 #4
    I will try to answer assuming the chain to be Elastic and massless.

    Please verify my approach and tell if there is any problem.
    There are 3 pictures. .... You will understand the sequence.
     

    Attached Files:

  6. Oct 6, 2016 #5
    I am really Sorry for the Emoticons.... I was in Hurry and somehow my Browser added them.

    But they are not a Problem to Understand the Theory, Fortunately!
     
  7. Oct 6, 2016 #6

    jbriggs444

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    The problem is not well posed. The amount of acceleration is not determined by the information given. Presumably you envision a chain as an inextensible, perfectly flexible massless cord attached to a rigid car and an unmoving anchor. If so, the force would be infinite. But that is unphysical. No car is perfectly rigid, no chain is inextensible or massless and no anchor is perfect.
     
  8. Oct 6, 2016 #7
    I am terribly sorry if I was not quite clear. What i meant was what would be the "shock" of force that would be an ime
    I see what you mean. I was trying to think of an equation that is essentially the same thing as a hammer hitting an anvil.
     
  9. Oct 6, 2016 #8

    jbriggs444

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    Yes, very much the same thing. An ideal hammer hitting an ideal anvil also results in an infinite force and cannot be physically realized.
     
  10. Oct 7, 2016 #9
    So what you are saying is that unless you involve elasticity into the equation, it would be an immense force that would be theoretically infinite.
     
  11. Oct 7, 2016 #10

    jbriggs444

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    Yes.

    There is a caveat. For a chain with non-zero mass, one might be able compute a finite answer, but the answer would depend [at least] on details of the mass of the chain, the shape of the links, the way it lays on the floor. That is because the chain will not come taut all at once. The links would need to rotate into place
     
  12. Oct 7, 2016 #11
    Thats an interesting thought. If we simplified it and went to the anvil idea. Would it not be just an equation that deals with the elasticity of the metal of the two?
     
  13. Oct 7, 2016 #12

    jbriggs444

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    Elasticity is part of it. But density also enters in. What is it that you actually want to determine here? And why?
     
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