A girl can easily lift an 80-N rock with the help of a lever.?

Question

When she pushes down with 10 N of force, she lifts the rock 0.1 meters. How far must she push the lever down to do this?

What is the formula for this? Can you explain your answer?

Answer 1

80N x 0.1m = 10N x "how far"

"how far" = (80N x 0.1m ) / 10N

"how far" = 0.8 meters

Answer 2

It's easy. (force x distance) is the same for both sides of a lever.

On the rock side you have 80N moving through 0.1m. On the girl side, you have a smaller force being applied, so the distance must be greater....

You have 10N moving through (0.1 x 80 / 10) = 0.8m