1. The problem statement, all variables and given/known data Here is the problem: A student pushes a 5.0 kg block at a constant speed 3 m across the ceiling of her room using a force Fa of magnitude 85 N and angle 75º. The coefficient of kinetic friction between the block and the ceiling is 0.40. Now, we must find the work done by the frictional force. 2. Relevant equations My Newton Second Laws: F, total,x direction= Facosθ-forcefriction=0 F, total, y direction=-Fn-mg+Fasinθ=0 3. The attempt at a solution When I solve for the force of friction, my answer comes out different depending on how I solve it. For instance, if I use my x direction relations, I would get forcefriction=facosθ. Thus, forcefriction would be 85cos75= 21.9996 If I solve the y eqn for fn, I get a normal force of 33.1. This multiplied by the kinetic constant (.4) is not 21.9996. What is causing the differences here in the friction forces?