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-   -   Asking physics questions? (https://www.askmehelpdesk.com/showthread.php?t=621839)

  • Dec 23, 2011, 08:36 AM
    ddilawarsingh
    Asking physics questions?
    A bullet of mass 10gm is fired from a rifle with velocity of 800 m/s. After passing through a wall of mud of 180 cm thick the velocity drops to 100m/s.The average force resisted by wall?
  • Dec 27, 2011, 12:41 AM
    Unknown008
    I'm assuming you have to ignore gravity here?

    Find the work done on the bullet by the wall taking the change in kinetic energy of the bullet :)

    Once you get that, use the work done equation (W = Fd) to get the force.

    One last thing, be careful with the units.
  • Dec 27, 2011, 09:44 AM
    ebaines
    Unk's aproach is probably the best for this problem, but just in case you haven't sudied about work and eneregy yet - another approach is to use one of the equations of motion to find the acceleration of the bullet:



    and then once you have a value for a use to find the force. You'll get the same answer, but without using work & energy principles.

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