By applying a 12-newton horizontal force, a 7-kilogram block is moved 12 meters in 3 seconds on a frictionless, horizontal surface. How much power was used in moving the block.

A) 144 watts

B) 112 watts

C) 16 watts

D) 48 watts

If a 12-N force is applied continuously through a distance

of 12m, then the amount of work done is

(force) x (distance) = (12 N) x (12 m) = 144 joules.

Power = (work done) / (time to do the work)

= (144 joules) / (3 sec) = 48 joules/sec = 48 watts.

We don't care what purpose the force was used for,

or how much friction was involved.