A 2.50 kg block is initially at rest on a horizontal surface. A horizontal force F of magnitude 6.71 N and a vertical force P are then applied to the block. The coefficients of friction for the block and surface are μs = 0.4 and μk = 0.25. Determine the magnitude of the frictional force acting on the block if the magnitude of P is (a)7.00 N and (b)10.0 N. (The upward pull is insufficient to move the block vertically.) relevant equations: F=ma Fk=μkFn Fs,max=μsFn attempt at solution: (2.50)(9.8)=24.5-7=17.5 net weight including upward pull of 7N (.4)(17.5)=7N so force 6.71N would not move block (.25)(17.5)=4.375N force of 6.71N would move block 6.71N-4.375N=2.335N On my online homework it said this was the wrong answer. Am I confusing coefficients I'm supposed to use at certain times? Thank you!