Energy - Definition, Types, Difference, FAQs
Have you ever thought about why a Bicycle moves when you press a pedal or why our body feels heat when we sit in the sun? These events occur because of Energy. The fact is that Energy can never be lost, and it is present in various forms. In this article, we will discuss energy in detail to understand the activities happening in everyday life.
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- What is Energy?
- Sources of Energy
- Energy Conservation Law
- What are the different forms of Energy?
What is Energy?
Energy Definition in Physics: The ability to do any work or cause any changes is called Energy. Energy exists in various forms, such as heat, light, electrical, chemical, and kinetic energy.
Unit of Energy
S.I. unit of energy is Joule (J). Energy is also expressed in many other non-SI system units. Many of these units include calories, ergs, kilowatt-hours, kilocalories, and British Units Thermal.
Examples of Energy
- When you lift a book, you’re using energy to move it.
- The sun provides energy in the form of light and heat, which warms our planet and enables plants to grow.
- Batteries store chemical energy, which powers devices when converted into electrical energy.
Sources of Energy
Sources of energy are the various forms from which we obtain energy in our daily life. These energy sources are classified into various forms:
Renewable energy sources
Energy resources that are present in abundant amounts in nature and won't be extinct are called Renewable energy resources. Some of the examples of Renewable energy sources are - Solar energy, Wind Energy, Hydropower, Biomass, and Geothermal Energy.
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Non-renewable energy sources
These types of energy sources are finite, which means it cannot be replenished easily as they are used up. They are less organic than renewable energy sources. Examples of non-renewable energy sources are- Coal, Nuclear Energy, Natural Gas, and Oil.
Secondary energy sources
Energy resources that do not occur naturally but can be generated from the primary resources available like coal, natural gas, solar, and wind are called Secondary energy sources. Examples of such resources are- Electricity, Refined Fuels like diesel, kerosene, and many others.
Energy Conservation Law
According to Law of Conservation of Energy- "An energy can neither be created nor destroyed, it can only transformed from one form to another." The total amount of energy in a closed system remains constant over time.
What are the different forms of Energy?
There are many different types of energy, which fall into two main categories: Potential energy and Kinetic energy. Let's look at the different types of energy and their respective examples.
Mechanical Energy
The mechanical energy $(M E)$ of an object is given by:
$$
M E=K E+P E
$$
where:
- $K E=$ Kinetic Energy, calculated as $\frac{1}{2} m v^2$,
- $P E=$ Potential Energy, calculated as $m g h$ (for gravitational potential energy),
Kinetic Energy
Kinetic force can be defined as the force of motion. When an object is in a state of motion, it is said to have kinetic energy. For example, running water, a moving ball, and more.
The formula to calculate Kinetic energy is:
$$
K E=\frac{1}{2} m v^2
$$
where:
- $m=$ Mass of the object (in kilograms, kg),
- $v=$ Velocity of the object (in meters per second, $\mathrm{m} / \mathrm{s}$ ).
Chemical Energy
Energy is stored in the bonds of chemical compounds, such as molecules and atoms are called as Chemical Energy. Chemical energy is a form of potential energy because it depends on the position and arrangement of atoms within molecules. Once the chemical energy is released from an object, it is usually converted into something completely new.
Light energy
Light energy is a type of electrical radiation. Light contains photons produced when the atoms of an object heat up. Light travels in waves and is the only source of energy visible to the human eye.
Light is made up of photons, which are small packets of energy. When the atomic matter is heated, photons are produced by the movement of atoms. Photons are produced according to the temperature of an object.
Heat Energy
Heat energy can also be called thermal energy, which is produced when rising temperatures cause molecules and atoms to move faster and more precisely. Examples of hot energy are heat from the sun, a cup of hot chocolate, baking in the oven, and heat from a heater.
Frequently Asked Questions (FAQs)
Gravity is stored at the height of an object
e.g. high gravity is stored on heavy and elevated objects. When someone climbs into a cliff and picks up speed, the force of gravity turns to the force of motion. Hydropower is another example of gravity, in which gravity forces water down a propeller to provide electricity.
Motion power is stored within the flow of objects. As soon as they go, a lot of energy is saved. It takes energy to persuade a moving object, and energy is released when the object is slow-moving. The wind is an example of the power of movement. A striking example of the force of movement can be a car collision - The car puts on a complete stop and releases all its movement power without delay in an uncontrolled moment.
According to the law of conservation, "Energy is not created, or destroyed, but can be changed from one form to another."
The energy we use is simply the conversion of other species. It has no specific sources. However, most of the energy we have used is the result of the Sun.
Looking at the representation above, it is clear that we need power. We get this energy from eating food, which is also derived from plants and animals. In fact, all animals, plants, fungi, viruses, bacteria, and other organisms need the energy to do all they can.
Other sources of renewable energy are solar energy, wind power, biomass and hydropower. It is called renewable because it is continuous. It is also called another form of energy as these are other forms of renewable energy.
Gravity is stored at the height of an object
e.g. high gravity is stored on heavy and elevated objects. When someone climbs into a cliff and picks up speed, the force of gravity turns to the force of motion. Hydropower is another example of gravity, in which gravity forces water down a propeller to provide electricity.
According to the law of conservation, "Energy is not created, or destroyed, but can be changed from one form to another."
The energy we use is simply the conversion of other species. It has no specific sources. However, most of the energy we have used is the result of the Sun.
Looking at the representation above, it is clear that we need power. We get this energy from eating food, which is also derived from plants and animals. In fact, all animals, plants, fungi, viruses, bacteria, and other organisms need the energy to do all they can.
Other sources of renewable energy are solar energy, wind power, biomass and hydropower. It is called renewable because it is continuous. It is also called another form of energy as these are other forms of renewable energy.
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Questions related to
n physics problems, the use of conservation of momentum and conservation of kinetic energy depends on the type of collision or interaction. Here's when to use each:
1. Conservation of Momentum
- Applicable to all types of collisions and interactions.
- Momentum is always conserved in a system where no external forces act.
Common Cases:
-
Elastic Collisions
- Momentum is conserved.
- Kinetic energy is also conserved.
- Example: Billiard balls colliding.
-
Inelastic Collisions
- Momentum is conserved.
- Kinetic energy is not conserved (some is lost as heat, sound, etc.).
- Example: Car crashes.
-
Perfectly Inelastic Collisions
- Momentum is conserved.
- Kinetic energy is not conserved.
- The objects stick together after the collision.
- Example: A lump of clay sticking to a moving cart.
-
Explosion Problems
- Momentum is conserved.
- Kinetic energy is not conserved (energy is released in different forms).
- Example: A bomb exploding into fragments.
2. Conservation of Kinetic Energy
- Only applicable in elastic collisions.
- In inelastic or perfectly inelastic collisions, kinetic energy is not conserved.
Common Cases:
-
Elastic Collisions
- Use both conservation of momentum and kinetic energy.
- Example: Two balls colliding with no energy loss.
When to Use Both Conservation of Momentum and Kinetic Energy
-
Elastic Collisions:
- Both momentum and kinetic energy are conserved.
- Example: Collisions between gas molecules in ideal conditions.
Summary:
| Collision Type | Momentum Conservation | Kinetic Energy Conservation | Example |
|---|---|---|---|
| Elastic Collision | Always | Yes | Billiard balls colliding |
| Inelastic Collision | Always | No | Car crash |
| Perfectly Inelastic | Always | No | Objects sticking together |
| Explosion | Always | No | Bomb exploding into fragments |
A body is thrown such that at the topmost point of its motion, its kinetic energy and potential energy are equal. The horizontal distance it covers (range) is given as 200 meters, and we are tasked with finding the maximum height it reaches.
When a body follows a projectile motion, its total energy is distributed between kinetic energy (due to its speed) and potential energy (due to its height). At the topmost point, since kinetic energy and potential energy are equal, half of the total energy is used to reach the height, and the other half contributes to the horizontal motion.
Using the properties of projectile motion, it can be determined that the maximum height reached by the body is one-fourth of the total horizontal distance covered. Therefore, if the range is 200 meters, the height will be:
200÷4=50 meters.200 \div 4 = 50 \, \text{meters}.200÷4=50meters.
Hence, the body rises to a height of 50 meters .
Key Formulas for Work, Energy, and Power in Class 9 Physics
Work done by a constant force:
- W = F × s
Where:
- W = Work done (Joule, J)
- F = Force applied (Newton, N)
- s = Displacement of the object in the direction of the force (meter, m)
Kinetic energy of a moving object:
- KE = 1/2 × m × v²
Where:
- KE = Kinetic energy (Joule, J)
- m = Mass of the object (kilogram, kg)
- v = Velocity of the object (meter/second, m/s)
Potential energy of an object at a height:
- PE = m × g × h
Where:
- PE = Potential energy (Joule, J)
- m = Mass of the object (kilogram, kg)
- g = Acceleration due to gravity (approximately 9.8 m/s²)
- h = Height of the object above the ground (meter, m)
Law of Conservation of Energy
- Total energy of an isolated system remains constant:
- Initial total energy = Final total energy
- Kinetic energy + Potential energy = Constant
Power:
- P = W / t
Where:
- P = Power (Watt, W)
- W = Work done (Joule, J)
- t = Time taken (second, s)
Hello,
A loudspeaker actually converts electrical energy into sound energy, not the other way around. This process involves the speaker's coils, magnets, and diaphragm working together to produce sound waves from electrical signals
Hope this helps,
Thank you
Hello there,
Emasters is a new form of education introduced in a very few NITs and IITs. Emaster in Renewable Energy is offered in IIT Kanpur. IIT Kanpur is the first IIT to introduce Emasters in Renewable Energy. Kindly check out their official site to get more information.
https://emasters.iitk.ac.in/course/masters-in-renewable-energy-and-emobility