A box with a mass 22kg is at rest on a ramp inclined at 45 degrees to the horizontal. The coefficients of friction between the box and the ramp are
static - 0.78
kinetic - 0.65

1. Determine the magnitude of the largest force that can be applied upward, parallel to the ramp, if the box is to remain at rest.

2. Determine the magnitude of the smallest force that can be applied onto the top of the box, perpendicular to the ramp, if the box is to remain at rest.

Question

A box with a mass 22kg is at rest on a ramp inclined at 45 degrees to the horizontal. The coefficients of friction between the box and the ramp are 
static - 0.78
kinetic - 0.65

1. Determine the magnitude of the largest force that can be applied upward, parallel to the ramp, if the box is to remain at rest.

2. Determine the magnitude of the smallest force that can be applied onto the top of the box, perpendicular to the ramp, if the box is to remain at rest.

anonymous · Answer

So...|dw:1373351145587:dw| Here is what the diagram looks like. The F kinetic = 0 in both x and y directions because you must remain at rest. Just find the F static max.