Please read till the end, before you answer. I'll start off with the examples to get to the point.
Drop a block from 1 meter and it will have speed v when it reaches the ground, with total work done on it w. Drop it from 2 meters and it won't have twice the speed, since it has less time to gain speed. Surprisingly, 2w work is done to it.
Another example. I know it's weird but it's important
A 1 Ton block of lead in space is at rest. A human is standing beside the lead block. The human is going to use chemical potential energy 2000 J to do work on the lead block and move it and displace it 2000 meters, using a force of 1 N on the block, Neglecting the force he uses to move himself to be able to push the block. How much time has he spent doing force?
Since force 1 N is done to on a 1 ton(1000 kg) block, and acceleration is force over mass, the acceleration is 1/1000. using the distance traveled by acceleration formula, the time needed is 2000 seconds. He has increased the momentum of the object from 0 to 2 thousand.
In another scenario, A human used 2000 J chemical potential energy using force 1 N on a 1 ton block of lead, but this time it was moving with a speed 50 m/s. The amount of time he would need to move it would of be less than 20 seconds, because of the block's speed. The increase in momentum of the object must be less than 20. Surprisingly, In both scenarios the human used chemical potential energy 2000 J, which is absurd, because the one in the first scenario must have used more energy.
Tl;Dr 2 humans consume the same amount of joules but the first uses so much "effort" and the second guy uses no effort but in the end, same joules consumed.
This is what I'm trying to say. The amount of work you have done is affected significantly by the initial speed of the object. What consumes more food(energy) , adding 2, 000 momentum to an object or 20? Physics tries to tell me they use the same energy?I don't understand how in each of the scenarios the human consumed the same amount of Joules even though he clearly would be so much more tired after pushing the block at rest than the moving block . This absurdity is slowly driving me insane. Where did I mess up?