Potential and Kinetic Energy and Energy Transformations

What is ENERGY?  Energy is the ability to do work or cause change.

You are about to learn…..  Some energy makes things happen right away.  Other energy is saved to make things happen at another time.  One type of energy can change into a variety of other kinds.  Energy is never really created or lost.

All energy is either kinetic or potential energy. What’s the difference?

Kinetic Energy  Kinetic energy is the energy of motion.

An object’s kinetic energy is determined by its mass and speed.  mass  speed

Potential Energy  Potential Energy is stored energy.

An object can have potential energy because of its position or because of what it is made of.  Position  What it’s made of

More examples of potential energy…  Position  What its made of

How much potential energy?  Position and mass can determine how much potential energy.

Potential Energy stored in an object can change into Kinetic Energy.  The boy has potential energy. If he jumps it is changed to kinetic energy.

Gravitational Potential Energy When gravity can change the potential energy to kinetic energy, the potential energy is called Gravitational Potential Energy.

Elastic Potential Energy  Energy stored in a stretched object that can snap back is called elastic potential energy.

Does a stick of wood have potential energy?  Before a log burns it has potential energy, but not because of position.  The energy is stored in the chemicals of the wood.  This is chemical potential energy.

Review so far…. Review so far….  All energy is kinetic or potential.  We have learned 3 forms of potential energy. Gravitational potential energyGravitational potential energy Elastic potential energyElastic potential energy Chemical potential energyChemical potential energy

Energy Transformations  Energy can change from one form to another.  When you flip a switch on a lamp, a cord carries electrical energy to the bulb where it is changed to light energy.

Energy Transformations  A light bulb also gets warm.  This is because some of the energy is changed into heat energy.

The Law of Conservation of Energy  Energy may change from one form to another, but energy is not created or destroyed.

Friction  Friction is a force that acts between the surfaces of materials that move against each other.

Friction changes some of the kinetic energy into heat energy.  Rub your hands together and feel the heat.

In Review …  Energy is kinetic or potential.  We learned 3 kinds of potential energy. What are they?  Potential energy can change to Kinetic energy.  Kinetic energy can change forms (electrical, light, heat, etc.)  Energy is not created or destroyed. It just changes forms.