In this article it says "It is commonly known that, if you accelerate an object, its mass will increase; however, to understand why this phenomenon occurs, we mustn’t think of the object’s mass increasing. Instead, we should think of its energy... when we speak of an objects mass increasing due to acceleration, we are really talking about its inertial mass increasing."
I understand that. But let's say I'm pushing a rock East at 100kph. I understand that if I suddenly wanted to push it West, I would be pushing the weight plus the momentum of the rock (the total of these would be the inertial mass). But if I only want to accelerate the object in the East direction, Does it take more energy for me to accelerate it from 1000kph to 1001kph than it took for me to accelerate it from 100kph to 101kph?
I have looked at all the links from questions like this, but I can't find that particular answer.