system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The scientific definition of work says that lifting 1lb 400 times is the same as lifting 400lb the same distance once(not counting negative motion). Why does it feel so different to our muscles?
gpt
1. You are also lifting your arm 400 times, and it has weight too.
2. Your body responds to more than the *amount of work,* it also responds to the *amount of force.* To take an extreme example, you cannot lift 4000 lb any distance at all.