What is the average useful power output (in W) of a person who does 6.60 ✕ 106 J of useful work in 8.40 h?

218.25 W.

Explanation:

Power: This is defined as the rate at which work is done. The S. I unit is Watt (W). Mathematically, it can be expressed as

P = W/t ... Equation 1.

Where P = useful power output, W = useful work, t = time taken to do the work.

Given: W = 6.6*10⁶ J, t = 8.4 h = 8.4*60*60 = 30240 s.

Substitute into equation 1

P = 6.6*10⁶/30240

P = 218.25 W.

Hence the useful power output = 218.25 W.