Conservation of Energy with Examples

Energy powers our world, allowing both living and non-living things to perform work. When a cat chases a mouse or a bus travels down the road, they’re converting energy into action. This fundamental principle is governed by the Law of Conservation of Energy, which states that energy can neither be created nor destroyed, only transformed from one form to another.

The conservation of energy principle touches every aspect of our daily lives, from simple activities to complex technologies. Let’s explore how this fundamental law works through practical, real-world examples.

What is energy and work?

Before diving into examples, it’s important to understand the relationship between work and energy. Energy is defined as the ‘capacity to do work’. The cat gets energy from food and the bus from gasoline. When the cat and the bus move, they have kinetic energy. So chemical energy from food and gasoline is converted to kinetic energy.

What are different types of energy in everyday life?

The conservation of energy principle operates across various energy types:

Chemical Energy: Stored in the bonds between atoms and molecules, released during chemical reactions
Thermal Energy: Heat energy from the movement of particles in matter
Solar Energy: Electromagnetic radiation from the sun that can be converted to other forms
Nuclear Energy: Released during nuclear fission or fusion when atomic nuclei change
Kinetic Energy: The energy of motion possessed by moving objects
Potential Energy: Stored energy based on an object’s position or state

Each of these energy forms can transform into others, but the total energy in a closed system remains constant—perfectly demonstrating the conservation of energy principle.

Energy conversion: is the process of converting one form of energy to another form. For example, on a cold night, we rub our hands together to keep ourselves warm. Here, kinetic energy from the rubbing of hands is converted to thermal energy.

What is conservation of energy ?

Conservation of energy states that

Energy can neither be created nor destroyed, but can only be transformed or transferred from one form to another.

For example, solar cell panels do not create energy but harness solar energy and convert it into electrical energy. Further, electrical energy can be converted into light and heat energy in our homes. So, energy changes forms but the total energy will remain the same in an isolated system.

Understanding conservation of energy with an experiment

Swing a pendulum and mark its positions. The extreme ends of the movement are labeled as A and B and the midpoint as C.

First, the ball is pulled to A from C. The K.E (Kinetic Energy) from our hand is converted into P.E (Potential Energy) and transferred to the ball.

So, at position A, P.E = maximum; K.E = 0 on the ball.

Now, the ball moves from A to reach C by converting its P.E to K.E. At C, P.E = 0; K.E = maximum on the ball.

As the ball has high kinetic energy, it will automatically move forward to B. At B, all the kinetic energy is converted to potential energy. As a result, P.E = maximum; K.E = 0 on the ball.

The ball momentarily pauses at B as the K.E = 0. But at this point, the stored P.E again gets converted to K.E making the ball move in the opposite direction.

However, the ball collides continuously with air molecules, losing its P.E and K.E to the air molecules. The ball will eventually come to rest.

FUN FACT: In contrast, in outer space there is no atmosphere and so there would be no collision between the ball and air molecules. There would be no loss of P.E and K.E and the swinging process would continue forever.

Examples of energy conversion

1. The conversion of chemical energy in food to mechanical to ride a bicycle.
2. The conversion of solar energy to chemical during photosynthesis in a plant.
3. The conversion of chemical energy stored in gasoline to mechanical energy to run a car.
4. The conversion of electrical energy into heat energy by in-room heaters.

What is sustainable energy ?

Certain energy conversions provide clean energy without polluting the atmosphere. Such energy conversion is called sustainable energy. The conversion of the kinetic energy of the wind to electrical energy to light our homes is clean energy. The conversion of solar energy to electrical energy is another example of sustainable energy.