Answer:
Power = 21[W]
Explanation:
Initial data:
F = 35[N]
d = 18[m]
In order to solve this problem we must remember the definition of work, which tells us that it is equal to the product of a force for a distance.
Therefore:
Work = W = F*d = 35*18 = 630 [J]
And power is defined as the amount of work performed in a time interval.
Power = Work / time
Time = t = 30[s]
Power = 630/30
Power = 21 [W]
The answer is a because it never needs to be insulated