Final answer:
The power the student exerted to move the desk is calculated by dividing the work done (force multiplied by distance) by time. The correct answer is 24 Watts, option (a).
Step-by-step explanation:
To calculate the power the student exerted to move the desk, we use the formula P = Fv, where P is power, F is force, and v is velocity. Since power is work done per unit time and work is the product of force and distance moved in the direction of the force, we need to calculate the work done and then divide by time.
In this case, the work done (W) is equal to the force (F) multiplied by the distance (d). So, W = 40 N × 12 m = 480 J. To find the power, divide the work done by the time, t, which is 20 seconds. Thus, P = 480 J / 20 s = 24 Watts.
Therefore, the power the student exerted to move the desk is 24 Watts, making option (a) the correct answer.