Kinetic Energy

What is Kinetic Energy?

Kinetic energy is defined as the energy that is produced by an object due to its motion. When an object is set to acceleration, there is a definite need to apply certain forces. The application of force needs work, and after the work is done, the energy gets transferred to the object making it move at a constant velocity. 

Here, the energy transferred is referred to as kinetic energy and depends on the speed and mass of the object being set in motion.

Fun Facts: As we move ahead on this page, you will understand how energy in an object changes from one form to another. For instance, take a flying squirrel that has collided with a chipmunk in its rest state. After the collision, there will be a flow of kinetic energy resulting in the squirrel to transform its energy into some other forms. It will come to rest and then the kinetic energy will be zero.

How can we Calculate Kinetic Energy?

In order to find out the kinetic energy, there needs to be some reasoning platform. Some of the findings are required, like the work done (W), by force (F). So, for instance, consider a box of mass m that is being pushed to a distance d because of the application of a force parallel to the surface. 

Looking at the definition of work done, it is the product of force and distance.

W​=F⋅d

=m⋅a⋅d​

From the kinematic equations of motion, it is stated that we could substitute the acceleration a if the initial and final velocity v and v0​ and the distance d. Is given:

So, from that, we derive: 

\[v^{2}\] = \[v_{0}^{2}\] + 2ad gives us a = \[\frac{v^{2}+v_{0}^{2}}{2d}\] 

When a net amount of work is done, the kinetic energy K does change.

Kinetic Energy: K=1/2​⋅m⋅v^2

In other words, the change in kinetic energy is equal to the net work done on a system or an object.

Wnet=ΔK

The above-mentioned formula is said to be the work-energy theorem and applies in a general sense. When forces act in different magnitudes and directions, it is imperative to know the conservative forces and conservation of energy. Here, the conservative force is a force where the total work done in any moving object between two definite points is independent of the path taken. Whereas, the conservation of energy states that the sum total energy of any isolated system doesn’t change over the time.

Examples of Kinetic Energy and Potential Energy

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Kinetic Energy Examples

Bearing in mind the above formula for kinetic energy, look at a few of the examples seen in everyday life situations. 

  1. An airplane has huge kinetic energy in flight because of its faster velocity and huge mass.

  2. A baseball after it is thrown, it will have a large amount of kinetic energy because of its high velocity, and despite its smaller size and mass.

  3. A downhill skier coming down from above will show immense kinetic energy because of its high velocity and mass.

  4. Before a golf ball has been struck shows zero kinetic energy as its velocity is zero.

  5. When an asteroid falls at an incredible speed, it has a huge amount of kinetic energy.

  6. A car traveling down the road has less kinetic energy as compared to that of a semi-truck because of the less mass of the car than the truck.

What is Potential Energy?

The form of energy by virtue of which energy is stored in an object due to some position and relative to some other position at rest is known as potential energy. Three types of energy effects are shown here viz: nuclear energy, chemical, and potential electrical. This can be measured based on the distance, height, or mass of the object. It is measured in Joules.

Examples of Potential Energy:

  1. A rocket sitting at the cliff's edge. When the rock falls, the potential energy gets converted to kinetic energy.

  2. Tree branches up high can fall into the ground, so they have potential energy.

  3. A dynamite stick has chemical potential energy. After the release, it will get fused to contact with the chemical; it will be activated.

  4. Foods that we intake provide us with energy due to the chemical potential energy. It helps with basic metabolic activities inside us.

  5. A spring stretched in a pinball machine can move the call after it is released. This produces elastic potential energy.

  6. Crane, when swings in a wrecking ball gain much energy even to crash the buildings

Kinetic Energy Units

When we take the unit of mass as kilogram and velocity as a meter per sec, the kinetic energy has the unit of kilograms meter square per Second Square. It is usually measured in Joules. So, the SI unit of kinetic energy is Joule (J), which is precisely 1kg.m^2.

FAQ (Frequently Asked Questions)

1. What are the Types of Kinetic Energy?

Kinetic energy does apply to everything that has movements. The faster the rate of motion of an object more will be its kinetic energy. Here, you'll find 5 types of kinetic energy.


a.  Radiant Energy


This is a type of kinetic energy due to the motion either through a medium or any space. For instance, ultraviolet light and gamma rays


b. Thermal Energy


This is also called heat energy that is generated because of the faster movement of atoms as they collide with one another. For eg: hot springs, heated swimming pools, etc.


c. Sound Energy


This is generated due to the object's vibration. It travels through any medium except through vacuum due to the void of any particles. For example, tuning fork, beating drums, etc.


d. Electrical Energy


This type of energy is found from free electrons (both +ve and –ve charges). For eg: lightning, batteries, etc.


e. Mechanical Energy


The sum of potential and kinetic energy is called mechanical energy. This energy can neither be created nor be destroyed and only can be transferred from one to another form. Its ex: a moving car, orbiting of a satellite around the earth's orbit.

2. What is Interesting about Kinetic Energy?

Some of the fun and interesting things on kinetic energy were derived through its equation is given as:

  • Kinetic energy relies on the object's velocity, and when the object doubles, the energy quadruples. 

  • It is not a vector unit, and the direction here doesn't matter. It only depends on the velocity with which it is thrown.

  • It should be either be o or +ve and the velocity should be +ve, or -ve