Final answer:
It's harder to move a full cart due to its greater mass and inertia, requiring more force to overcome it. Increased mass means more kinetic energy is needed for movement and more work is needed to stop. Surfaces with high friction also increase the required force.
Step-by-step explanation:
The reason it is harder to get a cart full of potatoes moving than one that is empty relates to the concept of inertia, which is directly linked to mass. According to Newton's first law of motion, an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. A cart full of potatoes has a greater mass than an empty cart, resulting in greater inertia. This means that the full cart will require more force to overcome this inertia and start moving. It is similar to the effort required to push a heavy object like a Humvee uphill; the greater the mass, the more energy is required to move it.
Additionally, once the cart is moving, kinetic energy is at play. An object with more mass will have more kinetic energy, which also means it will require more energy to stop. Imagine the difference between carrying a 24 N watermelon versus a 100 N TV; despite both items being carried to the same height, the TV requires more effort because of its greater mass and therefore more work is needed.
Furthermore, other factors such as friction can affect how much force is necessary to move the cart. A surface creating more friction will require more force to move the cart across it. Similarly, if two people are pushing on perpendicular sides of an object, the total effort required to move it is less compared to a single person pushing because the forces are not parallel and displacement is optimized.