1. The problem statement, all variables and given/known data A box is placed on an angeled surface. m = 15 kg f = 0,3 [PLAIN]http://img5.imageshack.us/img5/8717/friction.png [Broken] Will the box slip downwards if X = 0? How big does the force X have to be to push th box upwards? 2. Relevant equations 3. The attempt at a solution My idea was that the only force working upwards is Ff. A = 55° g = 9,81 N = mg*cos(90-35)+18 = 102,40 N Ff = 0,3*N = 30,72 Force downwards: mgcos35-18 = 102,54 N The force down is greater than Ff therefore it would slip if X = 0. To get how big X needs to be to make the box move up i simply subtracted the force down with Ff and got = 71,82 N. Could this possibly be correct?