Originally Posted by
bob152637485
I should really point out here that the units of the original question are completely wrong. It asks "How much power..." Technically, the answer would be 2.5MW/60 for one cycle of a sine wave. The answers are all in units of kWh, which is NOT power, but energy. The answer should either be changed to 41.7 kW, or the question changed to say energy instead of power.
EDIT:
The more I think about it, assuming the answer is meant to be power and not energy, I believe it would just remain 2.5MW, as opposed to dividing it by 60. The reason being is that the definition of power is joules/second, where energy is in joules(remember, there are 3.6 MJ in 1 kWh). In other words, it is a rate, not a quantity. Even if you only measured it for one cycle, as the question asks, the power would remain the same, just with less total energy. It would be like saying that if you drive down the highway at 60MPH, but stop driving after just 1 mile, you would have only been driving at a rate of 1MPH. That's simply not true, as during that one mile of driving, you still would have been traveling at a rate of 60MPH regardless of how far you decided to drive.
In this analogy, energy is your "miles" and power is your "MPH." Doesn't matter how "far" you drive, it has no effect on the rate you are traveling. In electrical terms, how much energy you use has no effect on your power, which is defined as a rate of energy per second. Whether I ask for the power over 1 cycle or 1 million cycles, the power would be 2.5MW at any point in time. Now ENERGY on the other hand, that we can define as our power times time, which will increase over time, and is clearly dependent on how much power we have. In math talk, you would say that power is the derivative of energy(the slope of the energy curve), or that energy is the integral of power(the area under the power curve).