system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How does a “double bounce” on a trampoline work?
gpt
Simple: it transfers one person’s energy to another’s via the springs.

Somewhat complicated: a person on a trampoline is converting energy all the time. Off the mat, you’re trading kinetic energy and gravitational potential energy. On the mat, you’re also trading in the potential energy of the “spring”. At the lowest point, you have no kinetic energy, minimal gravitational potential energy and the spring has its maximum potential energy.
At the point where you leave the mat, the spring has given you all its potential energy, primarily in the form of kinetic energy.

A double bounce is best performed when two people land concurrently, but one (at the lowest point) collapses their legs. The spring still has all the potential energy, and it goes into one person’s kinetic energy, throwing them much higher than before.