ELI5; When you have an absurd gear reduction, why is it harder to turn the final gear?

Question

I honestly don’t get this. I see these absurd gear reduction videos, 25k:1, Googol:1, etc. The first gear is easy to turn but the last barely turns due to gear reduction. They always show themselves trying to turn the last gear by hand and it doesn’t turn easilly. Why is that the case? why can’t the last gear become the first if you turn it first?

In: Engineering

Answer 1

To turn the final gear you have to apply the same amount of total force necessary to turn it by spinning the first gear. So if it takes 25,000 rotations of the first gear to turn the final gear, it would take 25,000 times the amount of force to turn the final gear than it does to turn the first gear.