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Reaction between two forces

  • 03-11-2010 5:15pm
    #1
    Ste234
    Registered Users, Registered Users 2 Posts: 65 ✭✭


    A 7 kg pallet carries a 25 kg bag of cement is lifted vertically upwards by a force of 352 N. Find the reaction between the pallet and the bag.
    Can someone show me how to do this please


Comments

  • #2
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Ste234 wrote: »
    A 7 kg pallet carries a 25 kg bag of cement is lifted vertically upwards by a force of 352 N. Find the reaction between the pallet and the bag.
    Can someone show me how to do this please

    The question is a little ambiguous. Is 352 the net force, or the force of of the crane doing the lifting? I will assume it is the latter.

    First, determine the gravitational force of the bag and pallet: F = 32xg

    where g is acceleration due to gravity.

    Then determine the net force: N = 352-F

    Work out the upward acceleration due to this net force : a = N / 32

    The force exerted on the bag by the pallet will therefore be a reactionary force due to gravity plus a reactionary force due to this acceleration:

    Ans = 7g + 7a


  • #3
    Ste234
    Registered Users, Registered Users 2 Posts: 65 ✭✭Ste234


    Should the reaction between the bag and pallet not be equal?
    but its not in this case cause wouldn't it be
    -25xg+25xa?


  • #4
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Ste234 wrote: »
    Should the reaction between the bag and pallet not be equal?

    The force exerted on the pallet by the bag will also be 7g+7a. 7g will correspond to the force due to the weight typical of the bag. 7a will correspond to a pseudo-force due to the pallet being in a non-inertial reference frame. In a sense, the bag is heavier in the reference frame of the pallet.


  • #5
    Pablo_
    Registered Users, Registered Users 2 Posts: 188 ✭✭Pablo_


    Ste234 wrote: »
    A 7 kg pallet carries a 25 kg bag of cement is lifted vertically upwards by a force of 352 N. Find the reaction between the pallet and the bag.
    Can someone show me how to do this please


    how did you get on with this que? did joe mark it harshly ??:D:D


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