Energy & Work

The Law of the Conservation

of Energy

Lesson #3

Lesson Objectives

Where does the Earth get most of its energy?

How is energy changed?

What is the law of the conservation of energy?

The Law of the Conservation of Energy

States: Energy can neither be created or destroyed

Energy can only change form!

The amount of energy that was present in the universe when the universe began is still the amount of energy in the universe.  The energy has only changes in form. 

  Energy can neither be created or destroyed Energy can only change form!

 The Sun

The sun is the sourc 

Light from the sun (solar energy) directly 
warms and lights our earth, giving our earth energy.  

The sun’s energy is stored in plants, or changed into
 one of the many natural sources of energy. (Wind, tidal, fossil fuels, etc.)

Plants (the only organisms that can directly use the suns energy) take the sun’s energy and 

Animals must get the sun’s energy by eating plants or by eating other animal that eat plants.

Changing of Energy

Sun Source of earth’s energy, Solar Energy.

Plant by the process of Photosynthesis change the suns energy into sugars and change the sun’s energy from solar energy to stored chemical energy.

Animals eat plants.  Animals obtain the sun’s energy from the stored chemical energy in the plants.

Through digestion (chemical energy) the energy is turned into the energy that our bodies need to work, and think.

When we exercise we use the energy that we get from the foods we eat. 

The chemical energy from the food is turned into mechanical energy that our bodies use to move about.

Whenever energy changes from one form to another some of the energy is changed to heat that radiates off the object like our bodies when we get hot from exercising.

The heat energy escapes then into the universe as entropy.

Once Again

Sun Source of earth’s energy, Solar Energy.

Plant by the process of Photosynthesis change the suns energy into sugars and change the sun’s energy from solar energy to stored chemical energy.

Over millions of years large amounts of plant and animal matter is chemically changed into fossil fuels, oil, coal, or natural gas.  In these fuels is stored energy from the sun.

Oil can be chemically changed into gasoline, a fuel used in automobiles.

In the engine of the automobile the gasoline is burned (chemical energy). The energy in the gasoline is changed into mechanical energy that makes the automobile move down the road.

Again, whenever energy changes from one form to another some of the energy is changed

The heat energy escapes then into the universe as entropy.