To push a box up a ramp, which requires less force: pushing horizontally or pushing parallel to the ramp? Why?

The force is described as an external agent that mainly changes the rest of motion of a particular object. The force is described as the product of the mass and the acceleration of an object.

The free body diagram of the box has been drawn below:

From the above diagram, it can be identified that the horizontal force mainly has two components in the horizontal and in the vertical direction. The reason for that force is that the normal force increases with the increase in the horizontal push. It eventually increases the frictional force that opposes motion and also less amount of net force is being exerted in the upward direction. Hence, for achieving the same amount of force in the upward direction, a greater amount of force is needed when pushing in the horizontal direction.

Thus, pushing parallel to the ramp requires less force.