What Is A Stored Energy That Has The Ability To Do Work Called?

Energy comes in many different forms and serves various functions in our world. Fundamentally, there are two main types of energy that describe how energy exists and flows: potential energy and kinetic energy. Potential energy refers to stored energy that has the potential to do work, while kinetic energy is energy associated with motion and actively doing work. The interplay and transfer between potential and kinetic energy drives many essential processes.

Potential Energy

Potential energy is energy that is stored and held in readiness. It is energy that has the potential to do work. Potential energy may be stored in a variety of ways including:

  • Gravitational potential energy – Objects can store energy based on their height and mass. For example, a bowling ball held up high on a shelf has more potential energy than when it is sitting on the ground.
  • Elastic potential energy – Elastic materials like springs or rubber bands can stretch and store energy that can be released when they snap back to their original shape.
  • Chemical potential energy – The bonds between atoms in molecules and compounds contain stored energy that can be released in chemical reactions.
  • Nuclear potential energy – Energy is stored in the bonds between protons and neutrons in the nucleus of an atom.
  • Electrostatic potential energy – Charged particles like electrons and protons create electric fields and can hold potential energy.
  • Magnetic potential energy – Current flowing in a coil of wire generates a magnetic field which stores energy.

These are some common forms of potential energy. This energy has the potential to be converted into kinetic energy, or energy of motion and do work. The amount of potential energy stored depends on the object or system. Understanding potential energy is key to explaining how energy transfers and transforms in the physical world.

Kinetic Energy

Kinetic energy is the energy of motion. Any object that is moving has kinetic energy. The amount of kinetic energy an object has depends on its mass and velocity. The greater the mass and velocity, the more kinetic energy the object will have. For example, a car moving at high speed has a large amount of kinetic energy, while a tennis ball moving slowly has much less kinetic energy.

Kinetic energy can also take the form of vibrational energy, rotational energy, electrical energy, thermal energy, electromagnetic radiation, sound and light. Vibrational kinetic energy is the energy stored in the vibrations of atoms and molecules in solids. Rotational kinetic energy is the energy associated with the spinning motion of an object. Electrical kinetic energy involves the movement of electrons. Thermal kinetic energy is the internal energy of an object associated with the random motion of its molecules and atoms. Light is a form of electromagnetic radiation that exhibits wave-particle duality, having both wave-like and particle-like properties. Sound is a vibration that propagates as an audible wave of alternating pressure.

In summary, kinetic energy represents the energy of motion, which can take many different forms at both the macroscopic and microscopic levels. The faster an object moves, the more kinetic energy it possesses.

Conversion Between Potential and Kinetic Energy

Potential energy can convert into kinetic energy, and vice versa. This conversion happens constantly in the world around us.

For example, when you hold an object above the ground, it has potential energy due to gravity acting on its mass. When you drop the object, gravity accelerates it and it gains kinetic energy as it falls. The potential energy is converted into kinetic energy.

The opposite can also happen. Think about a ball being thrown upwards. Initially the ball has kinetic energy from the throw. As it travels upwards against gravity, the ball slows down as the kinetic energy is converted into potential energy. At the balls highest point, it has maximum potential energy and no kinetic energy.

This energy conversion applies to many systems, like springs, pendulums, and roller coasters. The key is that total energy is always conserved in these transfers between potential and kinetic energy.

Units of Energy

Energy is measured in a variety of units, both in the SI (International System of Units) and imperial measurement systems. Here are some of the common units used to measure energy:

  • Joule (J) – This is the standard SI unit for measuring energy. One joule is defined as the amount of work done when a force of one newton moves an object one meter.
  • Calorie (cal) – This is a common imperial unit for measuring heat energy. One calorie is the amount of heat energy needed to raise one gram of water by one degree Celsius.
  • Kilojoule (kJ) – This is equal to 1,000 joules.
  • Kilocalorie (kcal) – Also known as food Calorie (upper case C), this is equal to 1,000 calories.
  • Watt-hour (Wh) – A unit of energy equal to one watt of power expended over one hour.
  • Kilowatt-hour (kWh) – Equal to 1,000 watt-hours. This is a common unit used for electrical energy.
  • British Thermal Unit (BTU) – A traditional unit of heat energy equal to about 1055 joules.
  • Therm (thm) – A unit of heat energy equal to 100,000 BTU.
  • Quad (quad) – Equal to one quadrillion (1015) BTU. Used to measure large amounts of energy.

These are some of the main units used to quantify energy across different systems and applications. The joule is the standard base unit, while larger or smaller units are commonly used for convenience.

Law of Conservation of Energy

One of the most important principles governing energy is the law of conservation of energy. This law states that energy can neither be created nor destroyed – it can only be transformed from one form into another. For example, when a ball drops, its potential energy gets converted into kinetic energy as it falls. The total amount of energy before and after the drop remains constant.

This law applies to all isolated or closed systems, where no energy can enter or leave. However, most systems in reality are open systems, where energy can cross the boundaries of the system. In those cases, while energy is conserved overall across the universe, the total energy within a system can change with the transfer of energy in and out.

The law of conservation of energy is crucial for describing how energy flows and transforms within a system. It allows us to track where energy comes from and where it ultimately ends up. This law has profound implications, indicating that energy itself cannot be created out of nothing or reduced to nothing. It can only change forms in a fixed overall quantity.

Forms of Energy

Energy comes in many different forms that can be categorized into two main types – potential energy and kinetic energy. Some of the most common forms of energy include:

Mechanical Energy – the energy stored in objects by tension or position. Examples are a stretched spring or object held at an elevated position.

Chemical Energy – energy stored in the bonds between atoms and molecules. Batteries and foods contain chemical energy.

Thermal Energy – the internal energy of an object or system due to the motion of particles and atoms.

Radiant Energy – energy in the form of electromagnetic waves such as light, radio waves, gamma rays, etc.

Nuclear Energy – the energy stored within an atom’s nucleus and released during nuclear reactions.

Electrical Energy – energy from the movement of charged particles such as protons, electrons, and ions.

Sound Energy – the energy carried by sound waves through vibrations in matter.

Energy can convert between these different forms, but the total energy remains constant according to the law of conservation of energy.

Energy Storage

Energy storage refers to the capture of energy for use at a later time. There are many different ways that energy can be stored.

One common example is batteries. Batteries store chemical energy that can be released as electrical energy. Rechargeable batteries like those found in phones and laptops can be charged with electricity and discharged to power devices.

Dams are another form of energy storage. Dams use the potential energy of water held at an elevated height to generate hydroelectric power on demand. Pumped storage hydroelectric plants pump water uphill to a reservoir during times of excess power generation so it can be released to generate electricity when needed.

Fuels like gasoline, diesel, and natural gas are forms of stored chemical energy. The combustion of these fuels releases energy that can be used for transportation, electricity generation, and other applications.

Renewable energy sources like solar and wind exhibit variability based on weather conditions, so energy storage helps integrate them into the grid. Batteries paired with solar arrays store excess daytime energy for nighttime use. Compressed air energy storage and flywheel energy storage are other ways to capture energy from renewables.

On a smaller scale, compressed springs and elevated weights are traditional mechanical forms of energy storage. Capacitors and inductors store electric and magnetic energy. Phase change materials and thermal energy storage capture heat for later use.

Energy storage allows energy to be held until needed and converted on demand. It provides flexibility and reliability in energy systems.

Energy Use in Daily Life

Energy is an essential part of our daily lives. Here are some examples of how we use energy on a regular basis:

In our homes, we use energy for lighting, heating and cooling systems, appliances, electronic devices, and more. Some major energy uses are:

  • Heating and cooling – Energy is needed to keep homes at a comfortable temperature through the use of furnaces, air conditioners, heat pumps, etc.
  • Hot water – Energy is used to heat water for bathing, washing dishes, etc. This is often done with natural gas, propane or electricity.
  • Appliances – Devices like refrigerators, stoves, dishwashers, washing machines and dryers all require energy to operate.
  • Electronics – Televisions, computers, tablets, game consoles and other devices need electrical energy to work.
  • Lighting – Energy is used to illuminate homes through lighting fixtures, lamps, and light bulbs.

For transportation, energy is used to power various vehicles that move people and goods:

  • Cars, trucks, and buses – Gasoline or diesel fuel is burned to provide energy to operate private and public road vehicles.
  • Planes – Jet fuel powers aircraft for passenger and freight air travel.
  • Trains – Diesel locomotives pull many passenger and freight trains.
  • Ships – Container ships, cruise ships, oil tankers and other vessels burn bunker fuel oil for propulsion.

At work and school, energy is used to power buildings, equipment, and activities:

  • Lighting, heating, and cooling office buildings and classrooms.
  • Operating computers, printers, machinery, and other equipment.
  • Performing industrial processes like manufacturing, mining, or agricultural work.

In summary, we use energy constantly throughout our daily lives for transportation, in our homes, at work and school, and for all types of activities and tasks.


As we have explored in this article, energy is the ability to do work. It comes in many different forms such as kinetic energy, potential energy, chemical energy, nuclear energy, electrical energy and more. Energy can be converted from one form to another, for example potential energy can be converted to kinetic energy when an object falls. A key concept is that energy is conserved – it cannot be created or destroyed, only converted between different forms.

Energy can also be stored for later use. Batteries store chemical energy, dams store potential energy in reservoirs, and food stores chemical energy that our bodies use. Being able to store energy allows us to have access to it even when its source is not continuously available, like solar or wind power. This stored energy can then be used to do useful work.

Energy powers our modern society. Understanding energy, how we harness it, convert it, store it, and use it, is key for powering our future sustainably and efficiently. Energy enables us to do work, produce goods, provide services and transport ourselves. Having an overview of what energy is and how we use it helps illustrate how essential yet invisible it is in our daily lives.

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