Conservation of Energy

9SCIE - Energy for Life

Finn LeSueur


Ngā Whāinga Ako

  • Be able to describe the law of conservation of energy
  • Be able to give examples of the law of conservation of energy

Types of Energy

Recall from last class the different types of energy:

  1. Active
  2. Potential
Potential Active
Chemical Kinetic
Gravitational Heat
Elastic Radiant
Nuclear Electric
Magnetic Sound

For each of the following pictures, write down what the picture is showing you and the type of energy associated with it.

NB: Not a real photo

Law of Conservation of Energy

If you can remember it, write it down in your book without looking, otherwise go to the next kiriata!

Energy cannot be created or destroyed, only transferred or transformed from one type to another.

The Pendulum

  • The bowling ball has some gravitational potential energy before it is released,
  • because energy is not created or destroyed, as long as he does not push the ball it can never get higher than it started,
  • this means that it will never hit him in the face

Another good tauria of the conservation of energy is in hydroelectric power generation. Watch this video to find out about one portion of New Zealand’s hydroelectric scheme.

Hydroelectric Power Generation

  • When water is high up a hill it has gravitational potential energy, that is, it has the potential to flow downhill
  • By allowing the water to flow downhill (gravitational -> kinetic) through turbines we can spin some generators transforming that kinetic energy into electrical energy
  • By turning some of that kinetic energy into electrical energy, the water loses kinetic energy and thus, slows down
  • When we use electricity to boil the jug we are converting electrical energy into heat energy!

What Is Energy?

  • Energy is the ability to do work, the ability or potential to effect some change on the environment or surroundings
  • E.g. the ability to lift something up, to heat something up, to push back (trampoline), to fall etc.

Perpetual Motion?

You may have heard of perpetual motion machines - machines that create infinite energy!

These machines appear to run forever, producing energy forever without consuming any energy.

Unfortunately, they are always a scam! People have been trying to make them since the dark ages but can all be shown to not work due to the law of conservation of energy!