The Physics of Swinging My son begs to watch me swing on one of the swings in the park. I tell him there is so much work to do and I don't know if I have the energy to do all the things needed to make a swing. It's a truly innocent plea, but complicated in terms of the actual trial. The physics of swinging has so many components. From resonance to strength and from oscillation period to energy conversion, the oscillation process is actually a complicated matter. As you watch a person swing, place your hand at the highest point of the swing's height and then count how many seconds it takes to return to the same height. You just measured the swing period. The period of the swing is the time it takes for the swing to make a complete back and forth motion. The equation used to solve the period mathematically is T = 2p (square root of L/g), where L is the length of the pendulum and g is gravity. There are a few things that can change the period of a pendulum. As the length increases and the force of gravity increases, the period will also increase. Likewise, when both gravity and chain length decrease, the period also decreases. My reference Mark Nethercott says that if there are no external influences, the period remains constant at about 15 degrees of arc, but the amplitude must be low. This statement corresponds to Newton's first law of motion (law of inertia) which says: "Every object remains at rest or in motion in a straight line at constant speed unless an unbalanced force intervenes." (Physics, A View of the World p.31). A force other than gravity and swing length can alter the outcome of a period. While standing with your hand outstretched, measuring the period, give the person on the swing a push. interval. So as you push the person on the swing, you create a form of resonance for the swing.” –Mark Nethercott. There is one final force that changes the period of a swing, and that is squatting and standing, or leaning back and forth.