What is energy?

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What is energy?

• By Mrs. Joshu

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Learning Objective

• Students will compare potential energy and
  kinetic energy.

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Key Terms

• energy
• potential energy
• kinetic energy

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Energy

• Energy is the ability to do work.
• Energy in its various forms is necessary for all
  sorts of changes. (So another way of defining
  energy is the ability to cause change.)
• One unit in which energy is measured is the joule
  (J).

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Forms of Energy

• Mechanical Energy Energy associated with
  motion.
• Heat Energy The internal motion of particles of
  matter. Heat energy often causes changes in the
  temperature and phase of any form of matter.
• Chemical Energy The energy that bonds atoms or
  ions together.

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Forms of Energy contd

• Electromagnetic Energy Moving electric charges.
  Light is a form of electromagnetic energy.
• Nuclear Energy The nucleus of an atom is the
  source of numlear energy. Nuclear energy is the
  most concentrated form of energy

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Kinetic and Potential Energy

• The five forms of energy can be classified as
  potential energy (energy of position) or kinetic
  energy (energy of motion). Because potential and
  kinetic energy most often have to do with motion,
  they are often treated as kinds of mechanical
  energy.

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Kinetic Energy

• Kinetic energy is energy of motion
• Anything that is moving has kinetic energy.
• Kinetic energy depends on two factors.
• With kinetic energy, the factors are mass and
  velocity.
• The faster you move, the more kinetic energy you
  have.
• The more mass a moving object has, the more
  kinetic energy it has.

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• Both runners are moving at the same speed.
• Because the runner on the left has more mass, he
  also has more kinetic energy than the runner on
  the right.

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Potential Energy

• Potential energy is stored energy.
• The gravitational potential energy stored in a
  sample of matter depends on two factors.
• These factors are mass and height.
• The more mass an object has, the more potential
  energy it has.
• Potential energy also depends on height.
• The farther an object has to fall, the more
  potential energy it has.

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Potential Energy contd

• Fireworks have a different kind of potential
  energy called chemical potential energy.
• This potential energy is stored in the chemicals
  in the fireworks.
• When the fireworks are set off, the potential
  energy stored in the chemicals is released as
  heat, light, and sound.

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What kind of Potential energy?
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Conservation of Energy

• The law of conservation of energy states that
  energy can be neither created nor destroyed by
  ordinary means. Energy can only be converted
  from one form to another. (Energy conversions
  occur without loss or gain in energy)

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Checking Concepts

• The ability to make something happen is
  ____________.
• Two kinds of energy are potential energy and
  _______________ energy.
• Stored energy is ___________ energy.
• Kinetic energy is energy of ______________.
• A diver on a diving board has _________________
  potential energy.

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Answers

• Energy
• Kinetic
• Potential
• Motion
• Gravitational

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In your lab book complete the following

• Describe the conversion between potential energy
  and kinetic energy as a tennis ball drops, hits
  the ground and bounces back up.

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The End