Nature of Energy



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Nature of Energy

  • Energy is all around you!
    • You can hear energy as sound.
    • You can see energy as light.
    • And you can feel it as wind.

Nature of Energy

  • You use energy when you:
    • hit a softball.
    • lift your book bag.
    • compress a spring.

Nature of Energy

  • Living organisms need energy for growth and movement.

Nature of Energy

  • Energy is involved when:
    • a bird flies.
    • a bomb explodes.
    • rain falls from the sky.
    • electricity flows in a wire.

Nature of Energy

  • What is energy that it can be involved in so many different activities?
    • Energy can be defined as the ability to do work.
    • If an object or organism does work (exerts a force over a distance to move an object) the object or organism uses energy.

Nature of Energy

  • Because of the direct connection between energy and work, energy is measured in the same unit as work: joules (J).
  • In addition to using energy to do work, objects gain energy because work is being done on them.

Forms of Energy

  • The five main forms of energy are:
    • Heat
    • Chemical
    • Electromagnetic
    • Nuclear
    • Mechanical

Heat Energy

  • The internal motion of the atoms is called heat energy, because moving particles produce heat.
  • Heat energy can be produced by friction.
  • Heat energy causes changes in temperature and phase of any form of matter.

Chemical Energy

  • Chemical Energy is required to bond atoms together.
  • And when bonds are broken, energy is released.

Chemical Energy

  • Fuel and food are forms of stored chemical energy.

Electromagnetic Energy

  • Power lines carry electromagnetic energy into your home in the form of electricity.

Electromagnetic Energy

  • Light is a form of electromagnetic energy.
  • Each color of light (Roy G Bv) represents a different amount of electromagnetic energy.
  • Electromagnetic Energy is also carried by X-rays, radio waves, and laser light.

Nuclear Energy

  • The nucleus of an atom is the source of nuclear energy.

Nuclear Energy

  • When the nucleus splits (fission), nuclear energy is released in the form of heat energy and light energy.
  • Nuclear energy is also released when nuclei collide at high speeds and join (fuse).

Nuclear Energy

  • The sun’s energy is produced from a nuclear fusion reaction in which hydrogen nuclei fuse to form helium nuclei.

Nuclear Energy

  • Nuclear energy is the most concentrated form of energy.
  • Most of us live within 10 miles of the Surry Nuclear Power Plant which converts nuclear energy into electromagnetic energy.

Mechanical Energy

  • When work is done to an object, it acquires energy. The energy it acquires is known as mechanical energy.

Mechanical Energy

  • When you kick a football, you give mechancal energy to the football to make it move.

Mechanical Energy

  • When you throw a balling ball, you give it energy. When that bowling ball hits the pins, some of the energy is transferred to the pins (transfer of momentum).

Energy Conversion

  • Energy can be changed from one form to another. Changes in the form of energy are called energy conversions.

Energy conversions

  • All forms of energy can be converted into other forms.
    • The sun’s energy through solar cells can be converted directly into electricity.
    • Green plants convert the sun’s energy (electromagnetic) into starches and sugars (chemical energy).

Other energy conversions

    • In an electric motor, electromagnetic energy is converted to mechanical energy.
    • In a battery, chemical energy is converted into electromagnetic energy.
    • The mechanical energy of a waterfall is converted to electrical energy in a generator.

Energy Conversions

  • In an automobile engine, fuel is burned to convert chemical energy into heat energy. The heat energy is then changed into mechanical energy.

Chemical  Heat Mechanical

States of Energy

  • The most common energy conversion is the conversion between potential and kinetic energy.
  • All forms of energy can be in either of two states:
    • Potential
    • Kinetic

States of Energy: Kinetic and Potential Energy

  • Kinetic Energy is the energy of motion.
  • Potential Energy is stored energy.

Kinetic Energy

  • The energy of motion is called kinetic energy.
  • The faster an object moves, the more kinetic energy it has.
  • The greater the mass of a moving object, the more kinetic energy it has.
  • Kinetic energy depends on both mass and velocity.

Kinetic Energy

  • K.E. = mass x velocity
  • 2
  • What has a greater affect of kinetic energy, mass or velocity? Why?
  • 2

Potential Energy

  • Potential Energy is stored energy.
    • Stored chemically in fuel, the nucleus of atom, and in foods.
    • Or stored because of the work done on it:
      • Stretching a rubber band.
      • Winding a watch.
      • Pulling back on a bow’s arrow.
      • Lifting a brick high in the air.

Gravitational Potential Energy

  • Potential energy that is dependent on height is called gravitational potential energy.

Potential Energy

  • Energy that is stored due to being stretched or compressed is called elastic potential energy.

Gravitational Potential Energy

  • A waterfall, a suspension bridge, and a falling snowflake all have gravitational potential energy.

Gravitational Potential Energy

  • If you stand on a 3-meter diving board, you have 3 times the G.P.E, than you had on a 1-meter diving board.

Gravitational Potential Energy

  • “The bigger they are the harder they fall” is not just a saying. It’s true. Objects with more mass have greater G.P.E.
  • The formula to find G.P.E. is
  • G.P.E. = Weight X Height.

Kinetic-Potential Energy Conversion

  • Roller coasters work because of the energy that is built into the system. Initially, the cars are pulled mechanically up the tallest hill, giving them a great deal of potential energy. From that point, the conversion between potential and kinetic energy powers the cars throughout the entire ride.

Kinetic vs. Potential Energy

  • At the point of maximum potential energy, the car has minimum kinetic energy.

Kinetic-Potential Energy Conversions

  • As a basketball player throws the ball into the air, various energy conversions take place.
  • Ball speeds up

The Law of Conservation of Energy

  • Energy can be neither created nor destroyed by ordinary means.
    • It can only be converted from one form to another.
    • If energy seems to disappear, then scientists look for it – leading to many important discoveries.

Law of Conservation of Energy

  • In 1905, Albert Einstein said that mass and energy can be converted into each other.
  • He showed that if matter is destroyed, energy is created, and if energy is destroyed mass is created. 2
          • E = MC

Vocabulary Words

  • energy
  • mechanical energy
  • heat energy
  • chemical energy
  • electromagnetic energy
  • nuclear energy
  • kinetic energy
  • potential energy
  • gravitational potential energy
  • energy conversion
  • Law of Conservation of Energy


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