You see a couple of trampolines on the playground. As you stand on one of them, you note it sinking down, as it pushes up on you, to keep you from moving further down. When you are standing, it pushes up on you just as much as the gravitational force from the Earth pulls you down.

What happens as you start to bounce? As you push to jump, the trampoline bed moves down bit extra, in order to push you up with a larger force, making you accelerate upwards. When you leave the trampoline bed, it returns to its unloaded position – until you land again. The higher you bounce, the more the trampoline bed is extended, in order to stop you fall as you land – and the send you up again.

The image to the right shows the forces acting during different parts of the motion. In the air, the only force acting is gravity, mg. In the lowest point, a much larger force upward force, N, from the trampoline bed is needed to stop the motion and provide acceleration for the next bounce. Also, note the changing length of the spiral, depending on the for from the feet of the toy animal. As it accelerates upwards, it need a larger force, making the spiral longer. While the bouncer is in the air, the spiral is instead completely contracted. It looks like the weight of the feet is gone – the toy is "weightless".