A block of mass 20kg is pushed against a vertical wall by force P. The coefficient of friction between the surface and the block is 0.2. If theta = 30 degrees, what is the minimum magnitude of P to hold the block still?I understand that in order for the block to sit motionless, the net forces acting on the block must be zero. I set my equation to be Net Force = 0 = Psin(theta) + Force Friction - Force Gravity.Which I rearranged as P = (Force Gravity - Force Friction)/sin(theta) or P = (mg-μ(mg))/sin(theta)Doing this gives me a value of 313.6N rather than 202.9N which I should be getting. What am I doing wrong?

Question

A block of mass 20kg is pushed against a vertical wall by force P. The coefficient of friction between the surface and the block is 0.2. If theta = 30 degrees, what is the minimum magnitude of P to hold the block still?
I understand that in order for the block to sit motionless, the net forces acting on the block must be zero. I set my equation to be Net Force = 0 = Psin(theta) + Force Friction - Force Gravity.
Which I rearranged as P = (Force Gravity - Force Friction)/sin(theta) or P = (mg-μ(mg))/sin(theta)
Doing this gives me a value of 313.6N rather than 202.9N which I should be getting. What am I doing wrong?

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