A box weighing 20lb. is being pushed up an incline. If the angle of incline was 90° to the ground, what effort would be needed to push the mass?
I don't get how to get the effort if an angle was in the problem.
You are looking for the weight component down the plane, that is what you have to overcome to go up the incline.
Weird: 90 degrees is straight up.
Effort has to be the same as weight. 20lbs.