# Mechanics question help?

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#1
A particle P of weight 8N rests on a horizontal surface. A horizontal force of magnitude 3N acts on P, and P is in limiting equilibrium .
i) calculate the coefficient of friction ( i worked this out as 3/8)
ii) find the magnitude and direction of the contact force exerted by the surface on P.

the only contact force I have been taught about is the normal contact force, which would surely just be 8 (same as the weight) I don't understand why it's not, can somebody help please
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4 years ago
#2
(Original post by ali_blue)
A particle P of weight 8N rests on a horizontal surface. A horizontal force of magnitude 3N acts on P, and P is in limiting equilibrium .
i) calculate the coefficient of friction ( i worked this out as 3/8)
ii) find the magnitude and direction of the contact force exerted by the surface on P.

the only contact force I have been taught about is the normal contact force, which would surely just be 8 (same as the weight) I don't understand why it's not, can somebody help please
The normal force acting at the point of contact is the normal component of the contact force. The frictional force is the horizontal component of the contact force.

To find the overall contact force you need to add the two together as vectors.
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