Work Done by a Constant Force

Steps:

• Identify the force applied by the student: average force F.
• Determine the displacement: distance d along the direction of the force.
• Recall the work formula for a force parallel to displacement: W = F × d.
• Apply the formula directly, as the table is horizontal and no angle is involved.

Why A is correct:

• Work done by a force is defined as the product of the force and the displacement in the direction of the force (W = Fd).

Why the others are wrong:

• B: Divides by g, which is gravitational field strength and irrelevant to the horizontal pushing force.
• C: Uses mass m times d, which has units of momentum, not energy.
• D: Equals mgh, the formula for gravitational potential energy change, not work by the applied force.

Final answer: A