Work requires net force causing displacement

Steps:

• Recall work $W = \vec{F} \cdot \vec{d}$, done when force has a component along displacement.
• Evaluate each option for applied force and object motion.
• Identify where force causes displacement in its direction.
• Confirm the scenario with both force and motion.

Why C is correct:

• Pushing applies a force parallel to the ramp's displacement, so $W = F \cdot d \cos 0^\circ = Fd > 0$, per work-energy theorem.

Why the others are wrong:

• A: Constant velocity means net force is zero, so no work by net force.
• B: Object is stationary, so displacement $d = 0$, work is zero.
• D: Stationary object means $d = 0$, buoyant force balances weight with no net work.

Final answer: C