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Weight of impact is from an object of 40kg that falls 50cm

  1. Dec 20, 2009 #1
    Hi,

    I have a basic question that i would be very thankful if someone could help me answer.

    I need to find out what the weight of impact is from an object of 40kg that falls 50cm.

    Many thanks.

    Jeanette
     
  2. jcsd
  3. Dec 20, 2009 #2

    russ_watters

    User Avatar

    Staff: Mentor

    Welcom to PF.

    The force an object imparts at impact is extremely difficult to determine with math alone (and isn't constant throughout the impact anyway). It depends on the material properties and geometry of the object being dropped and the object being hit.

    The best you can do with ease is impact energy, which for a dropped object far below terminal velocity is just e=mgh

    If you know the deceleration, though, you can use f=ma. If you drop a hard object on a hard floor, the deceleration can be hundreds of g's.
     
  4. Dec 21, 2009 #3
    I would first find the velocity at the moment of impact

    D = 1/2*a*t^2
    .5 = 1/2*9.8*t^2

    t=.319

    Vf = Vo + a*t^2
    Vf = 0 + 9.8*.319 = 3.13 m/s

    The time it takes to lose velocity (or acceleration) can depend upon what surface it's hitting, way it lands etc. as mentioned in the above post. But the force of impact will be the mass times the acceleration (velocity divided by time it takes to go from 3.13 m/s to 0 m/s). Hope this helped, and I also hope I didn't make a mistake on silly kinematics equations.
     
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