Hey. Ive been given this problem: "An person wishes to push a box up a hill, inclined at 30 degrees. He is able to push with a force of 450N. If the box has a mass of 20kg, and a force of friction with magnitude 20N applies, what is the acceleration of the box?" I drew a diagram, and came up with this: http://img135.imageshack.us/img135/1124/incplaneob0.gif [Broken] What i did was resolve all of the forces into their components (parallel and perpendicular to the slope), including the weight and normal force, and then add them all. I got an answer of 16.6 [tex]ms^-2[/tex], but apparently the answer is 1.9 [tex]ms^-2[/tex]. Would someone be able to maybe quickly work it out, and tell me what the real answer is? Thanks very much, Dan.