system
Given the following post, respond as if you're commenting on Reddit:
human
Why can people lift so much on a leg press?

I know people that can leg press like 600 lbs but can only squat about a quarter of that.

So I was wondering what the differences were? I was able to determine, using high school physics, that because the weight rests on the sled at about a 45° angle, only about 71% of the weight is effectively being lifted in the direction the sled travels.

However, this didn't satisfy me because a 600 lb leg press does not mean a 424 lb squat. So what else factors into this??
gpt
A few more things to consider, besides the lower force required to move the mass, would be a shorter range of motion and musculature involved. 

Most leg press machines don't allow the range of motion that a barbell squat does, effectivly cutting the amount of work being done.

Most people's squat is not being held back by lack of leg strength, but by their ability to support the weight with their core musculature (abs, lats, spinal erectors, etc). You're  not required to support the weight on your shoulders in the leg press and are therefore not limited by core strength. The solid back support does the work so your muscles don't have to.