Young gymnast Nya learns how Hooke's Law relates to the trampoline. Springs secure the mat to the metal frame, and scientist Robert Hooke discovered that the force of a spring is proportional to the force put upon the spring. So the higher you jump on a trampoline, the more the spring is stretched and the greater the return force. Pro jumper Thomas demonstrates how keeping his knees fairly straight and keeping his eyes fixed forward helps him accomplish his amazing moves.  Micro-gravity, the feeling of weightlessness, is experienced by trampoline jumpers as they descend from a jump.  The trampoline was invented by George Nissen who was inspired by the net used under circus trapeze artists.