Energy is the building block of the universe. Energy can neither be created nor be destroyed, it just changes from one form to another. There are several forms of energy around us, for example, potential energy, electrical energy, rotational energy, vibrational energy, wind energy, solar energy, etc.

 

In this blog, we will study about the basic concept of kinetic energy. We will see the derivation formula and daily life examples of it.  

 

 

What is Kinetic Energy?

 

Kinetic energy is defined as the energy of motion. It is gained by a body or an object because of the motion it exhibits. The kinetic energy of an object depends on the mass and speed of it. Kinetic energy can also be transformed from one object to another.

 

Any object in motion has a kinetic energy. The motion can be horizontal as well as vertical too. There are different forms of kinetic energy, these include:

 

1. Vibrational kinetic energy: Energy due to the vibrational motion.

 

2. Rotational kinetic energy: Energy due to rotational motion.

 

3. Translational kinetic energy: Energy due to motion of objects from one location to another.

 

Consider an object, as we apply force on the object, it accelerates. The work done by you is now transformed as an energy to the object. This energy is known as Kinetic Energy.

 

Also Read | Greenhouse Effects

 

Important Facts of Kinetic Energy

 

Following are the interesting facts related to the kinetic energy:

 

1. Kinetic energy is the square of the velocity. In simple words, if the velocity of an object doubles, its kinetic energy quadruples. For consideration, a car traveling at 40 mph has four times more kinetic energy than the identical car traveling at the speed of 20 mph.

 

2.  Kinetic energy can either be zero or positive. It can never be negative even when the velocity of the object is negative, the square formula turns it into a positive value.

 

3. Kinetic energy is a scalar quantity. Unlike Vector quantity it is direction independent. A car moving in a forward direction will have the same kinetic energy while moving in a backward direction with the same velocity.

 

How to Calculate Kinetic Energy?

 

Kinetic Energy is calculated in two ways. One is defined from rigid bodies and the other is defined for rotating bodies. Classical mechanics states that Kinetic Energy for a point object depends on the mass of the object and its speed.

 

Thus, the formula for Kinetic Energy is defined as,

 

K.E. = ½ mv2

 

Where, m= mass of the object and v is the velocity of the object. 

 

In the terms of work done and displacement kinetic energy is defined as,

 

K.E.= net force*displacement.

 

The kinetic energy can also be defined in the terms of momentum. The kinetic energy related to the momentum of an object is formulated as,

 

K.E.= p2/2m

 

Where, p is the momentum of the object and m is again the mass of the object.

 

Adding a fact, kinetic energy depends on the reference frame of an object. There is always a choice in the reference frame, and the frame which gives the minimum value for kinetic energy is called the center of the momentum frame. But the total energy of an isolated system remains the same always. This is called the Oberth effect.

 

For example, the translational kinetic energy is defined as,

 

K.E. (translational)= ½ mv2

 

Where, m is the center of mass of the object this time and v is the velocity.

 

In rotational mechanics, the kinetic energy of a body can be calculated using following formula,

 

K.E.= ½ Iw2

 

Also Read | Nuclear Energy

 

 

Kinetic Energy of a System

 

The Kinetic Energy of a system of bodies, where multiple bodies exist, is equal to the sum of Kinetic Energy of all the bodies of the system. These energies include all kinds of kinetic energies, for example, molecular transition, rotation, vibrational energy, spin energy, energy due to short motion and everything else.

 

For consideration, let us consider a real-life example. We all are aware of the solar system. A solar system consists of the sun and other eight planets. Basically, it is nothing but a system of different bodies of different masses. 

 

All the bodies are in motion. The sun and other planets are rotating on their own axis. Also, the other eight planets are revolving around the sun.

 

So basically, the total Kinetic Energy of this system is the sum of the kinetic energy of each planet, the Kinetic Energy of the sun, and the Kinetic Energies of all planets with respect to the sum. The reference frame of each case is different. But the net energy of the system is ultimately conserved.

 

Also Read | Fossil Fuels

 

 

Examples of Kinetic Energy in Real-Life

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Real-life examples of Kinetic Energy

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Now to understand kinetic energy more clearly, let us consider the examples from day-to-day life.

 

1. Hydropower Plants

 

Hydropower plants are used to generate electricity from the moving water. The moving water has some kinetic energy in it, when the same hits the turbine. The kinetic energy of water is converted into mechanical energy. Thus, the electricity is produced.

 

2. Wind Mills

 

Windmills are used to utilize wind into electrical energy. Moving winds consisting of kinetic energy in them, hit the blades of the wind mills. Thus, converted into mechanical energy, the kinetic energy helps in generating electricity.

 

3. Moving Car

 

A simple car accelerating or decelerating on the road also possesses some kinetic energy. But yes, it is directly proportional to the mass of the object. As if we compare the energies of a truck and a car moving with the same speed. The truck will definitely have more kinetic energy than the car.

 

4. A Flying Airplane

 

All the jets and airplanes flying in the sky possess kinetic energy because of their high velocity and huge masses.

 

5. Cycling and Playing

 

All human beings nearby showing any motion contain kinetic energy. Be it cycling, playing, skating, running, dancing, or simple walking. The motion having some velocity will always have some kinetic energy in it.

 

6. A Bullet from Gun

 

A bullet releasing from a gun has some high velocity and possesses’ high kinetic energy. This high kinetic energy of the gun helps it to penetrate through any object.

 

Despite these very examples, there are several other examples of kinetic energy around us. For consideration, a flying bird, a moving train, a moving object, flying kite, etc.

 

Also Read | Clean Energy

 

Energy can be used as a good source of development and progress. And it is high time to understand the importance of abundant and renewable energy sources and find ways to utilize them for productive and progressive activity.