During the summer, my sister (Janelle) and cousins (Kelsi-Ann and Staci) decided to use their trampoline as a water feature, putting the sprinkler directly under it. When they jumped on the trampoline, it propelled them upwards. They were in free fall for a couple of seconds, gravity being the only force. As they come down and hit the trampoline, it pushes back with an equal and opposite force, which once again pushes them upwards. This is an example of projectile motion since gravity is the only force acting on them. It is also an example of Newton's third law of motion, where every action has an equal and opposite reaction. If they didn't push off as soon as they landed, their second jump wouldn't be as high as the first.