Final answer:
The power expended by a force can be negative when the force acts opposite to an object's movement.
Step-by-step explanation:
The power expended by a force can indeed be negative. This occurs when the force is acting opposite to the direction of an object's displacement or, in other words, when the force does work on an object that is moving against the force's direction.
In cases such as friction slowing down a moving object, the force is taking energy out of the system, resulting in negative power. A 50-W light bulb can use more energy than a 1000-W oven if it is used for a longer duration. Power is the rate at which energy is used.
So if a lower-powered device is operated for a sufficiently long time, the total energy consumed could exceed that of a higher-powered device used for a shorter time. Energy consumption equals power multiplied by the time of usage.