system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: In movies and video games, why does it only look natural for giants and giant things to move slowly?

I've never seen a giant move at "normal" speed. They have to move their limbs more space, but they're also stronger so that should balance out, right?
gpt
Ok, so lets suppose your arm is 3 feet long. Now lets assume you have a giant doppleganger who has a 1000 foot arm.

You swat with your regular sized arm, moving 180 degrees in 1/4 of a second. That is a distance of about 9.5 feet, so your fingertips moved at almost 30 mph.

Now your double does the same swat with his 1000 foot arm, in the same amount of time. That is 3142 feet in 1/4 of a second, or 8570 mph. That is 11 times the speed of sound, or about half the speed of low Earth orbit. The hand is pulling a massive vacuum in its passing and the front is compressing air to the point of glowing white-hot. Assuming the flesh is relatively flesh-like it would be shredded, burned, and otherwise crushed by g-forces.