Mechanical energy is the sum of kinetic energy and potential energy in an object. Kinetic energy is the energy an object possesses due to its motion, while potential energy is the energy an object has due to its position or state.
According to the law of conservation of energy, mechanical energy is always conserved in a closed system. This means that the total amount of mechanical energy in the system remains constant, even though it may change forms or be transferred between different objects within the system.
One example of mechanical energy conservation is a pendulum. As the pendulum swings back and forth, it exchanges kinetic energy and potential energy. However, the total amount of mechanical energy in the system remains constant, and the pendulum will continue to swing at the same height and speed until an external force, such as friction, acts upon it.
Mechanical energy is closely related to work, as work is defined as the transfer of energy through the application of force. In order for work to be done, there must be a transfer of mechanical energy, either from one object to another or between different forms of mechanical energy.
Mechanical energy conservation has many real-world applications, such as in roller coasters, where the potential energy gained at the top of a hill is converted into kinetic energy as the roller coaster travels down the track. Other examples include wind turbines, where the kinetic energy of wind is converted into mechanical energy to generate electricity, and spring-loaded toys, where potential energy stored in a compressed spring is converted into kinetic energy when the toy is released.