Energy is needed to make something happen.  In science, energy is the ability to cause change or do work.

 In general, there are two types of energy: potential energy and kinetic energy.

 Each type has many forms. The nucleus of an atom stores nuclear energy.

Potential energy is stored energy. Four forms:

Elastic energy Chemical Nuclear energy Gravitational potential energy energy When an object is above the Earth’s surface, it has … gravitational potential energy (GPE). The amount of GPE an object has depends on: 1) Mass More GPE The amount of GPE an object has depends on*: 1) Mass 2) Height

Less GPE *It depends on the gravitational force too, but this force is about the same everywhere on earth.

 Which point does the girl have the most GPE? Where will the rollercoaster riders have the most gravitational potential energy? Where will the rollercoaster riders have the least gravitational potential energy? Who has the most GPE?

What information do we need to know before answering this question?

We need to know who has the most mass? Do the hamburger and matchstick have GPE?

Yes. Any object above the Earth’s surface has GPE.  Does a matchstick have other forms of energy stored in it? Where is it stored?

The head of the match contains chemicals.

Chemicals store a form of energy called CHEMICAL ENERGY. When the match is lit, the chemical energy is changed into other forms of energy such as.

CHEMICAL Other forms ENERGY of energy Food also contains chemical energy. So what exactly is chemical energy? Chemical energy is a type of potential energy stored in the bonds between atoms. Food contains glucose. The energy stored in glucose is released in cellular respiration.

Glucose

C6H12O6 The SI (Systeme Internationale) unit for energy is the joule.

Another common unit is the calorie. Eating food gives animals energy (the ability to do work). Without energy, we cannot run, walk and play. We cannot even breath!

The chemical energy is changed into CHEMICAL many other ENERGY forms! All of these objects have stored chemical energy that can be released and used. This rubber band has stored up another type of potential energy. This rubber band has stored up another type of potential energy.

Elastic energy is stored in objects that are stretched or squashed. This spring gains elastic energy when it is ….

Elastic energy is stored in objects that are stretched or squashed. This spring gains elastic energy when it is stretched or…

Elastic energy is stored in objects that are stretched or squashed. This spring gains elastic energy when it is stretched or compressed. (squashed)

Elastic energy is stored in objects that are stretched or squashed.  How do you know the tennis ball has elastic energy?  Nuclear energy is stored in the nucleus of atoms. (the center)  Released when nucleus splits or combines  The sun’s light and heat come from nuclear energy. Identify the type of potential energy

A rock on a mountain has…

gravitational potential energy

chemical energy

elastic energy

Nuclear energy Identify the type of potential energy A stretched bow has… elastic energy Identify the type of potential energy The nucleus of an atom has… nuclear energy Identify the type of potential energy

Soda has… chemical energy When the diver jumps, he changes GPE to kinetic energy. Kinetic energy is the energy associated with motion. Large objects and small objects can have kinetic energy.

Planets have kinetic energy Particles of matter do too! The more mass and speed an object has, the more kinetic energy it has.  Which ball has the most kinetic energy? 1 or 2? A or B? A moving object is so small that it can not be seen. Does it have kinetic energy?

There are special names for these forms of kinetic energy.

1) Electrical energy 2) Light energy 3) Sound energy 4) Heat energy Electrical energy is caused by the movement of electrons.  Electrical energy is very commonly found.

 Can you find some examples in the classroom?  A battery stores chemical energy (potential energy). When we use it, the energy is changed into electrical energy.

 What does the light bub do with the energy? Light energy is the energy that electromagnetic waves carry.

We can see only some of these waves.

Most of them Visible light cannot be seen. X-rays, microwaves and radio waves are also electromagnetic waves. The sun gives What is this process called? out light energy.

Plants can change this light energy Glucose gets changed to chemical energy (stored in glucose).  Sound energy is caused when an object vibrates. The vibrations cause waves to travel through the air or another material.

 We will study sound energy in detail later.  Thermal energy (heat) is due to the movement of the particles in an object.

 What is an example Hotter objects have more thermal energy because their particles are moving faster.

The nucleus of an atom stores nuclear energy. (Can be large or small objects) Before After

a) The energy gets used up and is gone. b) The energy get changed from one form to another. Before After

Chemical energy gets changed to electromagnetic energy (light)

and thermal energy (heat)  An energy transformation takes place when energy changes from one form to another.

Original energy Final energy