Kinetic Energy

Introduction

The term kinetic energy can be defined as the energy that is possessed by an object due to motion. It is, therefore, the force needed to make an object accelerate which has a particular mass to its required velocity. When the body gains this energy from acceleration, it maintains this energy until an external speed is applied to it. This form of energy not only depends upon the motion of the object but also depends upon its mass.

When kinetic energy is being transferred between objects, it gets transformed into other forms of energy. For instance, a flying phalanger collides with a stationary chipmunk. In this collision, the initial kinetic energy of the squirrel may have been transferred into the chipmunk or into another type of energy.

Units of Kinetic Energy

The kinetic energy of a body that gets transferred is equal to the product of the mass and square of the velocity when divided by 2. Therefore, the formula for kinetic energy can be written as:

                                 K.E= (½)mv2

The above formula is often valid just for the cases of transfer from low to relatively higher speeds. Except for extremely high-speed particles, it gives negligible values. When the speed of an object proceeds towards that of light (3 × 108 metres per second, or 186,000 miles per second), we can observe an increase in its mass and the laws of relativity come into play. The relativistic kinetic energy is equal to the rise in the mass of a particle at rest when multiplied by the square of the speed of light.

The unit of kinetic energy in the metre-kilogram-second system is represented as joule. A two-kilogram mass (approximately 4.4-pound weight on earth) moving at a speed of 1m/s encompasses a KE of 1 joule. But in the centimetre-gram-second system, the unit of kinetic energy is represented in erg. There are also some other units of energy that are used, like the eV, which is used in the atomic and subatomic scale.

Kinetic Energy Examples

Anything that has mass and motion can be an example of kinetic energy. Some of the examples of kinetic energies are as follows:

1. Motion of a bird or a flying jet
2. Car driving
3. Motion obtained during walking, jogging, bicycling, swimming, dancing
4. Throwing a ball
5. Falling of something
6. Spinning of a windmill
7. An avalanche
8. Motion of clouds across the sky
9. Launching a rocket
10. The wind
11. Flow of Electricity through a wire
12. A flowing stream
13. Meteors falling on the earth
14. Satellites that are orbiting
15. Orbits of electrons around the atomic nucleus
16. Movement of sound from a speaker to your ears
17. Waterfall (motion of water)

These are just some of the examples of kinetic energy. There can be many other examples.

Kinetic Energy Transformation

As you know, both potential energy and kinetic energy are relative. The chief relation between these two energies is the ability to transform into one another. That means potential energy can transform into kinetic energy, and kinetic energy can also convert into potential energy, and vice-versa. Hence, the transformation of kinetic energy is a never-ending cycle.

The processes that convert energy from one type (for example, kinetic, gravitational potential, chemical energy) into another are termed energy transformations. Any kind of energy use must involve some sort of kinetic energy transformation. As described in the first law of thermodynamics, energy can neither be created nor destroyed. However, it can get transformed from one type into another. In fact, in every process, there is energy transformation. 

There are many various kinds of energy. Some have greater importance while others have lesser. 

Kinetic energy and electricity are the foremost useful forms of energy. They have greater importance as they get transformed almost completely into the other kind of energy. For instance, electricity is easily accustomed to generating heat (thermal energy) or light (radiant energy), breaking chemical bonds (chemical energy), moving objects (kinetic energy), or lifting objects (gravitational potential energy).

Low-temperature thermal energy is of the least importance. It can be converted back to a superior form, but the energy is usually lost during this process. Trying to convert energy to a less-useful form than trying to figure it backwards never gets 100% of the useful energy back.

Consider this example: When a car is being run, the engine becomes hot (thermal energy). The amount of heat of the engine does nothing to assist the car is moving faster. This wastage of energy is a by-product and should be avoided during converting the car’s chemical energy into movement. However, it can be used for heating the car’s cabin and slightly increasing its overall energy efficiency. 

It has become a challenge in all kinds of power generation to reduce wasted energy. Nowadays, we use many thermal converters whose principles involve the transformation of thermal energy into electricity. The efficiency of such systems is thus subject to fundamental limitations. And, as dictated by the laws of thermodynamics and other scientific principles, considerable attention is a must to direct energy-conversion devices that can detour the intermediate step of conversion to heat in electric power generation.

This theory of energy conversion highlights the conventional systems. It can also act as an alternative for experimental converters with considerable potential energies. This theory depicts the basic principles of operation, its major types, and the key applications of energy conversion.

Types of Kinetic Energy

There are five forms of kinetic energy.

1. Radiant energy: It is a kind of kinetic energy that is always in motion and travels through medium or space. Some examples of radiant energy are ultraviolet radiation and Gamma rays.

2. Thermal energy: It can be referred to as heat, which is generated due to the motion of atoms after they hit one another. Some examples of thermal energy are hot springs and heated swimming pools.

3. Sound energy: It is produced due to the vibration of an object. This form of energy can travel through the medium but cannot travel in a vacuum due to the absence of any particles to act as a medium. Some examples of sound energy are tuning forks and beating drums.

4. Electrical energy: This kind of energy is obtained from the free electrons that are of positive and negative charge. Some examples of electricity are lightning and batteries when in use.

5. Mechanical energy: It can be referred to as the sum of kinetic energy and potential energy. Some examples of mechanical energy are the orbiting satellites around the earth and a moving car.

Conclusion

• Kinetic energy is contingent on the square of the speed of the object. This implies that when the speed of an object doubles, its KE quadruples. A car travelling at 60 mph has fourfold the kinetic energy of a uniform car travelling at 30 mph, and hence fourfold more potential of death and destruction in the event of a crash.
• Kinetic energy should always have a positive value, or its value may be zero at times. While velocity can have a positive or negative value, velocity squared is usually positive.
• Kinetic energy is not a vector quantity. Therefore, when a ball is thrown to the proper with a velocity of 5 m/s, it has the precise KE as a ball thrown down with a velocity of 5 m/s.