Law of conservation of energy
Whenever energy changes from one form to another form, the total amount of energy remains constant.
According to this law, energy can only be converted from one form to another; it can neither be created or destroyed. The total energy before and after the transformation remains the same. The law of conservation of energy is valid in all situations and for all kinds of transformation.
Conservation of energy during free fall of a body
- A ball of mass ‘m’ at a height ‘h’ has potential energy = mgh.
- As ball falls downwards, height ‘h’ decreases, so the potential energy also decreases.
- Kinetic energy at ‘h’ is zero but it is increasing during falling of ball.
- The sum of potential energy & kinetic energy of the ball remains the same at every point during its fall.
Kinetic energy + potential energy = Constant
1/2mv2 + mgh = constant
The sum of kinetic energy and potential energy of an object is its total mechanical energy.
During free fall of the object, the decreases in potential energy, at any point in its path, appears as an equal amount of increase in kinetic energy. There is thus a continual transformation of gravitational potential energy into kinetic energy.