system
Given the following post, respond as if you're commenting on Reddit:
human
[Bioshock Infinite] How does Booker not rip his left arm off when using the Sky-lines?
gpt
The skyhook is designed based on two principles, ensuring that your wrist doesn't break, and relying on forward momentum. 

The skyhook is designed with an arm brace, so that the shearing force doesn't do some damage. But the important thing is that you have to be moving in order for the thing to work. That forward momentum transfers the force that would rip his arm off into moving forward. Physics, basically.