Interconversion of energy:
Energy cannot be destroyed however it can be converted into some other forms.
1. Rub your hands together quickly. You will feel them warm. You have used your muscular energy in rubbing hands as a result heat is produced. In the process of rubbing hands, mechanical energy is converted into heat energy.
2. Processes in nature are the results of energy changes. For example, some of the heat energy from the Sun is taken up by the water in the oceans. This increases the thermal energy.
Thermal energy causes water to evaporate from the surface to form water vapors. These vapors rise and form clouds. As they cool down, they form water drops and fall as rain. Potential energy changes to kinetic energy as the rain falls, this rainwater may reach a lake or a dam. As the rainwater flows down, its kinetic energy changes into thermal energy while parts of the kinetic energy of flowing water are used to wash away soil particles of rocks known as soil erosion.
Note: During the interconversion of energy from one form to other forms, the total energy at any time remains constant.
DO YOU KNOW?
A pole vaulter uses a flexible vaulting pole made of special material. It is capable to store all the vaulter's kinetic energy while bending in the form of potential energy. The vaulter runs as fast as possible to gain speed. The kinetic energy gained by the pole vaulter due to speed helps him/her to rise as the vaulter straightens. Thus, he attains height as the pole returns the potential energy stored by the vaulter in the pole.