Question: State and explain one example where (i) Kinetic energy is present in a body and is used; and (ii) Potential energy is present in a body and is used
Hint:In order to answer this question, you must be aware about the concept of Potential energy and Kinetic energy. The sum of these two energies is called mechanical energy. According to the law of conservation of energy, the total energy of the system remains conserved.
Complete answer: (i) Kinetic energy is the energy that a body possesses as a result of its motion. When water is stored in a dam at a specific height, it is said to have maximum potential energy because the water is present at a specific height. This water is said to have kinetic energy when it is allowed to fall from a certain height. When water falls on a turbine, the paddle wheels rotate, causing the turbine to rotate. As a result, the kinetic energy of water is used to push or rotate the turbine which is then used to produce electricity.
(ii) Potential energy is present in a body as a result of its position. The kinetic energy of water used to rotate the turbine in a hydropower plant is obtained by utilising the potential energy of water stored in a dam. When water is stored in a dam at a certain height, potential energy is stored in the water, which is converted to kinetic energy when the water is released from the dam.
Note:Potential energy is position relative and kinetic energy is motion relative. The primary relationship between the two is their ability to transform into each other and hence keeping the total energy constant.