How Is the Force of Friction Calculated for a Block Against a Wall?

AI Thread Summary
To calculate the force of friction for a block against a wall, the relevant equation is Fk = µ (F sin θ - mg). Given a block mass of 2.3 kg, a coefficient of kinetic friction of 0.53, and an applied force of 68 N at an angle of 62 degrees, the gravitational force acting on the block is mg = 22.54 N. The vertical component of the applied force must balance the weight of the block, leading to the conclusion that the vertical forces must equal mg. A free body diagram helps visualize these forces, confirming that the vertical component of the applied force does indeed equal the weight of the block. The final calculation will yield the force of friction in Newtons.
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Homework Statement


As shown in the figure, a block is pushed up against the wall. Let the mass of the block be m=2.3 kg, the coefficient of kinetic friction between the block and the wall be µ= 0.53, and θ= 62. Suppose F = 68 N.
The acceleration of gravity is 9.8 m/s^2.
Find the force of friction. Answer in units of N.
http://img359.imageshack.us/my.php?image=71957582pz7.jpg
http://img359.imageshack.us/my.php?image=71957582pz7.jpg

Homework Equations


Fk= µ ( F sin θ - mg)
F=ma




The Attempt at a Solution


Well first I used F= µ(F sin θ), but I figured it was too simple, so I drew a free body diagram and saw mg going down on the block. I'm not sure how to go from there. Does the vertical component of force equal mg?
 
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Yes, the sum of the vertical components must be equal to the weight of the block.
 

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