Question is: "A box with a mass of 22kg is at rest on a ramp inclined at 45° to the horizontal. The coefficients of friction between the box and the ramp are µ(s) = 0.78 and µ(k) = 0.65 Determine the magnitude of the largest force that can be applied upward, parallel to the ramp, if the box is to remain at rest." What I was thinking, is that if the object is at rest, then the net force on the x axis is zero. So, the magnitude would be the same as the gravity parallel to the ramp...? My calculations: (22kg)(9.8N/kg)sin45° - F(applied) = 0N F(applied) = 152N Is that right, or wrong? Hints or suggestions...?