Kinetic and Potential Energy

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Kinetic and Potential Energy

• Physical Science

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What is energy?

• The ability to do work or cause change

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How do we measure energy?

• We measure energy in joules.

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Who is Joule?

• James Prescott Joule was from Great Britain
  (1818-1889). At the age of 16, he studied with
  the British chemist John Dalton. He began his
  independent research in a laboratory built at
  home where he hoped to replace steam engines by
  electric motors.
• He was also an inventor. He invented electrical
  welding and the displacement pump.
• The Joule, the unit of energy, was named in his
  honor.

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Mechanical Energy

• The energy you measure when you observe the
  motion and position of an object.
• There are two types of mechanical energy kinetic
  and potential.

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Kinetic Energy

• The energy an object has because it is in motion
• Examples are a moving rocket, a runner, etc.

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Potential Energy

• The energy an object has because of its position.
• Examples are a stretched guitar string, a right
  spring of a wind-up toy, a high diver, etc.

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Gravitational Potential Energy

• The energy an object has due to its height above
  the ground.

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Other forms of energy

• Chemical energy
• Thermal energy
• Electric energy
• Light energy
• Nuclear energy

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Chemical Energy

• Measures the effects of chemical reactions
• Example the reactions that occur when gasoline
  burns to provide the energy for cars and buses.

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Thermal Energy

• Heat energy
• Examples thermal energy can be detected in the
  engine of a running automobile as the temperature
  of its moving parts increases.

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Electric Energy

• Comes from the flow of electrons
• Examples we use electric energy to operate
  lights and appliances

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Light Energy

• Comes from the sun
• Examples plants convert light energy from the
  sun to chemical energy for their growth. Earth
  absorbs sunlight and releases thermal energy for
  a warm environment.

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Nuclear Energy

• Involves changes within the smallest particles of
  matter
• Some communities rely on nuclear energy to meet
  their energy needs.

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Conservation of Energy

• The law of conservation of energy states that
  energy can change from one form to another, but
  the total amount of energy is conserved.

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How do you calculate Kinetic Energy?

• The formula is KE (1/2)mv2
• For example A car with the mass of 200
  kilograms moving at 2 meters per second would
  have this kinetic energy
• KE (1/2)200 x 4
• KE 400 Joules

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How do you calculate gravitational potential
energy?

• The formula is GPE mgh
• For example If you dropped a 5 gram water
  balloon from 2 meters above the earth, the GPE
  would be
• GPE 5 x 9.8 x 2
• GPE 98 Joules