Let's think about power. $($a$)$ What is the average useful power output of a person who does $6\mathrm{.}00$x$10\backslash$deg J of useful work in $8\mathrm{.}00$ h$?($b$)$ Working at this rate, how long will it take this person to lift $2000$ kg of bricks $1\mathrm{.}50$ m to a platform? $($Work done to lift his body can be omitted because it is not considered useful output here