What can be done to double the power output of an object?

Answer: double the speed of the object.

Explanation:

From the definition of power, power is the rate at which work is done. That is,

Power P = Work done/time

But

Work done = force * distance

Work done = F*S

Substitute F * S for work done on power formula.

P = (F*S) / t

P = F * S/t

But S/t = velocity V

P = F * V

Since power P is proportional to speed V, to double the power output of an object, the speed V of the object must be doubled.