Final answer:
The power used is 15 watts.
Step-by-step explanation:
To calculate power, we use the formula:
Power (P) = Work (W) / Time (t)
In this case, the work done is 45J and the time taken is 3 seconds. Plugging these values into the formula:
Power (P) = 45J / 3s = 15W
Therefore, the power used is 15 watts.