Friction help. AP Physics C student

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To determine the frictional force acting on a 2.5 kg block under various vertical force magnitudes, the normal force must be calculated first. The normal force is affected by both the weight of the block and the applied vertical force. The frictional force can then be found using the coefficient of kinetic friction and the normal force. The discussion emphasizes the importance of correctly applying the equations for forces in both the vertical and horizontal directions. Understanding these concepts is crucial for solving the problem accurately.
bobAllan
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1. A 2.5 kg block is initially at rest on a horizontal surface. A horizontal force of magnitude F = 6.0 N and a vertical force of magnitude P are then applied to the block. The coefficients of friction for the block and surface are μ_s = 0.40 and μ_k = 0.25. Determine the magnitude of the frictional force acting on the block if ...
a) ...the magnitude of P is 8.0 N.

b) ...the magnitude of P is 10 N.

c) ...the magnitude of P is 12 N.


2

Fn=-mg
Ff=μFn



3.
honestly- not sure where to get started. i have the answers in the back of the book, but would really like to understand this and how to find hte solution
 
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Please show some attempt at a solution for further assistance. You listed a couple of relevant equations, but neither is quite correct. Look at all forces in the y direction to calculate the normal force, and look up again the formula for friction.
 
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