Final answer:
The correct answer to the question is that when an object is moving with constant velocity, the net force on the object is zero, which is answer choice (d). This is due to Newton's first law, which states that an object will continue in its state of constant velocity unless acted upon by a net external force.
Step-by-step explanation:
When an object is moving with constant velocity, we can make explicit conclusions about the forces acting upon it. According to Newton's first law of motion, an object in motion will remain in motion with a constant velocity unless acted upon by a net external force.
This principle tells us that if an object is moving at a constant velocity, the net force acting on the object must be zero. Therefore, there could be forces acting on the object, but they are balanced, and the frictional force could be equal and opposite to any force trying to slow the object down, balancing out the overall forces.
If the object were accelerating, then according to Newton's second law, a nonzero net force would be acting on the object resulting in a change in its momentum. However, since the object is not accelerating but moving with constant velocity, the correct answer to the student's question is 'The net force on the object is zero'. That answer is (d).