Category: 5. Potential and Kinetic Energy

Potential energy and kinetic energy are an indispensable part of our daily lives. From simple things like brushing your teeth to just standing – everything we do involves both forms of energy.   

You’ll find various forms of energy, ranging from thermal energy to sound energy to electrical energy. But if there is one thing that they all have in common: you can categorize all of these under potential energy or kinetic energy – and sometimes both.  

Kinetic energy and potential energy play a crucial role in making our earth greener too as they help create renewable sources of energy like wind energy. In short, we’re never not going to deal with these energy forms, especially since energy isn’t ever lost – it only changes form. 

Potential energy and kinetic energy are both measured in joules (J), named after the English mathematician, James Prescott Joule. But they have different formulas with respect to their different attributes.  

Potential energy depends on the force acting on the two objects, so its formula is:

Potential Energy = mgh  

• m is the mass measured in kilograms 
• g is the acceleration due to gravity 
• h is the height in meters 

Kinetic energy is directly proportional to an object’s mass and the square of its velocity. Putting it in a formula we get:  

Kinetic Energy = 1/2 m v²  

• m is the mass measured in kilograms 
• v is the velocity of meters per second 

With the specifics and variations out of the way, let’s examine energy further by considering how potential energy is described in other forms of studies. 

What Is Potential Energy in Physics? 

In physics, potential energy is the stored energy in an object due to its position relative to some zero position, which is an arbitrarily assigned position like the ground. It adheres to several physics-related laws, such as the law of conservation of energy and the first law of thermodynamics, which state that energy is always conserved and cannot be created or destroyed.

What Is Potential Energy in Chemistry? 

Chemical potential energy is the stored energy in the chemical bonds of a substance and is broken down through different chemical reactions. The newly generated chemical energy is used in different ways, also known as work.

Work is energy in motion. Hence, chemical potential energy remains true to the basic law: potential energy is converted to kinetic energy and never created or destroyed. 

The earth’s gravitational field is responsible for gravitational potential energy. The British Broadcasting Corporation describes this form of potential energy as the energy an object has by virtue of its position above the surface of the Earth.

You may have noticed that when a person dives, they always land with more force when making a splash into the swimming pool.   

*Enter earth’s gravity*  

The force of gravity uses the diver’s weight to produce kinetic energy (the diving motion) that causes the diver to splash into the pool. So, when the diver stands at the top of the diving board, it’s their gravitational potential energy, which is then converted into kinetic energy when they jump off the board. 

Chemical potential energy is the stored chemical bonds of a substance. When you charge a battery, the battery ends up storing the chemical potential energy, which is later converted to electrical energy.

There are six types of potential energy: mechanical energy, electrical energy, chemical energy, radiant energy, nuclear energy, and thermal energy.

However, our primary focus here is potential chemical potential energy and gravitational potential energy. 

Radiant energy is a form of kinetic energy that’s created when electromagnetic waves travel through space. It might surprise you to learn that the sun is one of the biggest sources of radiant energy on our planet.

Remember that warm feeling you get once you step out of the sun? It’s the sun’s radiant energy that touches our skin. More precisely, the electromagnetic waves make our skin’s molecules move faster, which, in turn, creates kinetic energy.

Thermal energy is just a fancy word for heat energy. It’s a form of both potential and kinetic energy.   

If you remember, the electrons of an atom have potential energy. Once you apply pressure to the electrons, they start to move rapidly, banging into each other, and releasing thermal energy as heat.   

Think of boiling water for a bit. Water, when placed on the stove, has potential energy. But once it starts to heat, the water molecules begin to move faster, creating kinetic energy.  

Thermal potential energy is potential energy at the atomic and molecular levels when the particles show the potential of converting into kinetic energy. On the other hand, thermal kinetic energy is when the atoms and molecules start moving due to heat and temperature.

Just like electrical energy, sound energy can be a type of potential energy as well as kinetic energy. But before getting into specifics, let’s understand what sound energy is. 

 Sound energy refers to the energy released by vibrating objects. Sound, though, is a wave that travels through a medium, such as air, which allows it to store kinetic energy and potential energy.

For instance, when you play the drums, they vibrate as a result of sound waves being emitted. These waves oscillate and travel, creating kinetic energy. But when the drums are left untouched, they have more potential energy since the equipment is not in motion and has the potential to make a sound. 

Electrical energy can be either potential or kinetic energy since it’s created from an electric charge flow.   

Continuing with the example of a battery, we know it has electrical potential energy while charging. But once you apply force to the battery, the charged particles start to do some work, converting the potential energy into kinetic energy.   

Similarly, when you switch on a light, the potential energy travels down your wiring and is converted into light and heat that are both forms of kinetic energy.