Energy

Science for Junior High School

2nd Semester Grade VIII

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Science Text Book Page 52-57

What is Energy

What are the forms of energy in terms of physics

A. What is Energy

                Energy is a "power" that makes the work occur. Which means it is the capacity of a physical system to work. It has many types of energies, those are chemical energy, thermal energy, sound energy, light energy, electrical energy, nuclear energy, and the most important mechanical energy. Since work and energy have a relation, energy is also Joules (J) like work. 

B. Forms of Energy

DEFINITION

EXAMPLES

                  As is explained above, there are many types of energy. Those are chemical energy, thermal energy, sound energy, light energy, electrical energy, nuclear energy, and mechanical energy. In this section B, I will going to explain each types of the energy, and also the definition of it.

1. Chemical Energy: Chemical energy is the energy mostly contained in your body. You can also find chemical energy in food, and some natural resources such as coal, oil, and natural gas. Joules (energy) that are produced by food is kept in the human body in order to perform activities. Most dominant energy resource of food is carbohydrates (rice, bread, grains) and also fat (Milk, butter, oil).

2. Thermal energy: Thermal energy is the energy related with the really small motion of particles producing a heat. You can find thermal energy by rubbing hands together, and also from everywhere that produces heat. Such as, a geyser. 

3. Sound energy: Sound energy is the energy produced through the vibration of air particles around a sound source.  Think of a car horn for an example. It produces vibration on air particles because of a strong sound

4. Light energy: Light energy is the energy produced by the radiation of electromagnetic waves. For an example, Earth gets brighten up because of the sun illuminating the darkness of the space near an Earth.

5. Electrical energy: Electrical energy is the energy produced by electrical charges which move through the cables. For example, a laptop is being charged by the charger which uses the electrical energy. 

6. Nuclear energy: Nuclear energy is the energy released from the reaction of the nucleus of radioactive matters. There are two kinds of nuclear energy; they are a fusion energy ( the join of the nucleus of an atom) and a fission energy (the split of the nucleus of an atom). Power plant is a great example of nuclear energy.The most visible source of nuclear energy are the more than 400 worldwide power plants that function on nuclear reactors. These reactors contain the reaction of nuclear fission, which produces heat that is then used to create electricity. More than 20 percent of power in the United States is produced by these power plants.

7. Mechanical energy: Mechanical energy is the energy associated with motion. Which means is an energy of an object due to its motion or position. Mechanical energy can be either kinetic energy (energy of motion) or potential energy (stored energy of position). A moving car possesses mechanical energy due to its motion (kinetic energy).A moving baseball possesses mechanical energy due to both its high speed (kinetic energy) and its vertical position above the ground (gravitational potential energy). A World Civilization book at rest on the top shelf of a locker possesses mechanical energy due to its vertical position above the ground (gravitational potential energy). A barbell lifted high above a weightlifter's head possesses mechanical energy due to its vertical position above the ground (gravitational potential energy). A drawn bow possesses mechanical energy due to its stretched position (elastic potential energy).