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    a particle of mass 3kg moves in straight line on rough surface. coefficient of friction between surface and particle is 6/49

    a) find the frictional force and show that the deceleration of particle is 1.2ms^-2

    i found that frictional force is 3.6N, correct me if im wrong

    but then no idea how to show the deceleration, i figured i'd use f=ma

    so p-3.6=3a

    there's 2 letters in there, and im stuck.
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    (Original post by ihatePE)
    a particle of mass 3kg moves in straight line on rough surface. coefficient of friction between surface and particle is 6/49

    a) find the frictional force and show that the deceleration of particle is 1.2ms^-2

    i found that frictional force is 3.6N, correct me if im wrong

    but then no idea how to show the deceleration, i figured i'd use f=ma

    so p-3.6=3a

    there's 2 letters in there, and im stuck.
    3.6N is correct.

    Now you want to resolve horizontally (in the direction of motion) using F=ma.

    The resultant force in the direction of motion is -F, which is -3.6 i.e. there is only a friction force present. Set this equal to ma and rearrange for a.
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    (Original post by SherlockHolmes)
    3.6N is correct.

    Now you want to resolve horizontally (in the direction of motion) using F=ma.

    The resultant force in the direction of motion is -F, which is -3.6 i.e. there is only a friction force present. Set this equal to ma and rearrange for a.
    that always get to me, i always automatically think there should be 2 force that should go in the F in f=ma.

    so:

    -3.6=3a?
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    (Original post by ihatePE)
    that always get to me, i always automatically think there should be 2 force that should go in the F in f=ma.

    so:

    -3.6=3a?
    Yes you should always draw a diagram and label all of the forces acting on the particle first before starting the question.

    Yes that's right. Rearranging gives a = -1.2
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    (Original post by SherlockHolmes)
    Yes you should always draw a diagram and label all of the forces acting on the particle first before starting the question.

    Yes that's right. Rearranging gives a = -1.2
    thank you, i can finally sleep tonight
 
 
 
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