Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newtonmeter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. A 1 hp machine does 550 ft⋅lb of work in 1 second and 1 hp equals 746 watts.
Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?
do 25 ft. lb. of work in 2 minutes 5 seconds 

do the work in 2 minutes 

do 100 ft. lb. of work in 4 minutes 12 seconds 

do the work in 3 minutes 