Swinging on a swing can provide an example of pendulum physics.
Pendulum physics is used to describe the swinging motion of a pendulum caused by gravity. To create a pendulum, a weight, called a bob, is hung from a fixed point, called a pivot. As you pull the pendulum back and release it, it will swing back and forth due to the force of gravity and tension along the rope or wire from which the weight is hanging. The motion continues by inertia.
According to the basic law of inertia, whether a body is at rest or in motion, it will remain in that state unless acted upon by an external force. In the case of pendulum physics, the pendulum will continue to swing unless an external force acts to stop it. Since no external force is acting on it, it can continue to oscillate indefinitely in the same arc.
The action of a pendulum is a good example of conservation of mechanical energy. This law of physics states that the energy within a system always remains constant. In other words, the sum of energy is always the same and energy cannot be created or destroyed. There are many different types of energy states that an object can be in, such as kinetic, potential, chemical, nuclear, and thermal. The states of potential and kinetic energy, or in motion, are those that are measured and observed in pendulum physics.
When a pendulum is swinging, its energy state changes based on the location of the arc the pendulum is in, but what remains the same is the sum total of the pendulum’s potential and kinetic energy – in other words, energy is conserved. . At the pendulum’s highest point, it has no velocity and all the energy in the system is potential. As it falls into the arc, the pendulum gains speed and kinetic energy while losing potential energy. Once it passes through the bottom of the arc, it begins to decelerate and loses kinetic energy while gaining height and potential energy. Although kinetic and potential energy vary, measurements of pendulum physics show that the total remains the same at all points of the pendulum’s arc.
In pendulum physics, air resistance and friction are assumed to be non-existent in the pendulum. Since the energy of a pendulum system is conserved, it is said to have perpetual motion, which can continue indefinitely as long as no energy is lost to other objects or surroundings. The fact that a pendulum continues to oscillate in the same way over time is why it was used in clocks to keep time and was initially used to make measurements of gravitational force.