Final answer:
Both gravitational force and friction act on the cart on the way up the ramp, with the frictional force being the one that changes direction depending on whether the cart is moving up or down.
Step-by-step explanation:
The forces that act on a cart on the way up a ramp after being pushed by a person are primarily the gravitational force, the frictional force, and the applied force from the person. The gravitational force acts downwards, directly towards the center of the Earth, and remains consistent in magnitude and direction.
The frictional force, which opposes the motion of the cart, acts parallel to the surface of the ramp and in the opposite direction of the cart's motion. This means that the frictional force has a different direction on the way up than on the way down the ramp.
While ascending, friction opposes the upward motion, and while descending, it opposes the downward motion. Lastly, the applied force from the person is the force in the direction of the push; this force does not inherently change direction with respect to the cart's movement up or down the ramp but is no longer present once the person stops pushing.
Considering these details, the correct answer to the question: "What forces act on the cart on the way up the ramp (after the push)? Does any force have a different direction on the way up than on the way down?" would be B) Both gravitational force and friction act on the cart, and friction has a different direction on the way up.