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The energy of the object possessed by an object in virtue of its position is called potential energy. The unit of Potential energy is Joules. There are two types of potential energy— gravitational potential energy and elastic potential energy    Ex: Some toy cars have a coiled spring inside them. This spring is compressed either by winding a key or by pulling the car backwards. The energy of the spring increases when it is compressed. When the car is released, this energy drives the car forward.

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The potential energy due to height above the earth’s surface is called gravitational potential energy. Look at fig. 5.10. Consider two positions of a ball of mass m one at A and the other at B. The position B is at a height h= AB above the position A. Suppose someone brings down the ball from B slowly. The ball exerts a force mg on the hand in the vertically downward direction. As the hand is displaced from B to A, the force exerted by the ball on the hand does some work. This work is,

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When a spring is stretched or compressed from its natural length, it gets extra energy. It can return to its natural length by performing some work. The extra energy stored in a stretched or compressed energy is called its elastic potential energy. A stretched rubber band also has elastic potential energy, whereas a rubber band at its natural length lying on a table has no electric potential energy.

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The Kinetic energy of an object is the energy it has when it is in motion. It is defined as the work that is needed to accelerate a body of a given mass from its rest position to a stated velocity . Having gained this energy during acceleration, the body maintains this until its speed changes . The same amount of work is done by the body when it is decelerating from its current speed to rest. Kinetic energy can also be transferred  to other objects and transformed into other kinds of energies.

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One of the commonest examples of kinetic  enrgy  is a cyclist who has chemical energy provided by his/her food to accelerate a bicycle to a chosen speed.. This process has converted chemical energy into kinetic energy but has also generated heat in the cyclist Another example is of a spacecraft that uses chemical energy of fuel to launch and gain considerable kinetic energy to reach orbital velocity.

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Law  of conservation of energy states that energy can neither be created nor be destroyed: IT can only be transformed from one from to the other. In an isolated system i.e., a system that is isolated from it surroundings, the total energy is conserved.

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https:// byjus.com /physics/law-of-conservation-of-energy/

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Mechanical energy is referred to as the sum total of the kinetic energy and potential energy in an object that is used to do a particular work. In other words, it describes the energy of an object because of its motion or position or both.

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Example of mechanical energy is a moving car possesses mechanical energy due to its motion (kinetic energy) and a barbell is lifted high above a weightlifter’s head possesses mechanical energy due to its vertical position above the ground (potential energy).

ENERGY

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