Six Olympic athletes described the delicate mechanics behind their chosen event. Here’s how they do what they do.

Jessica Stevens, 24

In no Olympic sport are Isaac Newton’s three laws of motion proved more regularly and conclusively than in trampoline. First Law: You stay at rest, or in motion, unless acted upon by an external force.

An external force, gravity, acts on Stevens throughout her routine. Even as she rises, she slows; she is in perpetual free fall, like an astronaut in orbit.