There's nothing wrong with my sentence. It might be a bit informal, but "power use for a length of time" is a quantity of energy. The decrease in speed you're

There's nothing wrong with my sentence. It might be a bit informal, but "power use for a length of time" is a quantity of energy. The decrease in speed you're describing is one time, not continuous. This is the issue both parent and I are pointing out. It's a shame to me that you aren't willing to see your error and instead resort to nitpicking, but I'm not going to try to explain a third time.