To determine the person’s power output, we first calculate the work done by the person in moving the box, and then we calculate the power.

Step 1: Calculate Work Done

The work $W$ done by a force $F$ over a distance $d$ is given by: $W = F \times d$ Given:

• Force, $F = 20 \, \text{N}$
• Distance, $d = 2 \, \text{m}$

$W = 20 \, \text{N} \times 2 \, \text{m} = 40 \, \text{J}$

Step 2: Calculate Power

Power $P$ is the rate at which work is done, which can be calculated by: $P = \frac{W}{t}$ where:

• $W = 40 \, \text{J}$
• Time, $t = 4 \, \text{s}$

$P = \frac{40 \, \text{J}}{4 \, \text{s}} = 10 \, \text{W}$

Answer:

The person's power output is 10 W, so the correct answer is: A. 10 W

Would you like a more detailed explanation of any step?

Here are some related questions to consider:

1. How would the power output change if the surface were not frictionless?
2. What would be the work done if the force applied was doubled?
3. How does the power output vary if the same work is done in half the time?
4. What is the kinetic energy of the box after moving 2 meters?
5. How would the scenario change if the force was applied at an angle?

Tip: Power can be thought of as the "speed" at which work is done—more power means work is done faster.