Energy Laws & Types

Energy: the ability to do work or cause change

Energy is always involved when physical or chemical changes occur in matter

You can detect the effects of energy when matter is moved, when it reacts, or when energy is transformed from one form to another form

Law of Conservation of Energy: Energy cannot be created or destroyed, it can only change from one form to another

2 Main Types of Energy: Potential or Kinetic

Potential energy is stored energy that has not been used.

Examples Potential Energy

Gasoline fuel) Food Batteries Potential energy

Pulled back Bow and Arrow A stretched back arrow has potential energy

Rollercoaster at top of hill Potential energy at top of coaster. Rocks on top of a cliff

Pressure building inside a volcano before it erupts Geologic faults before an earthquake

When the position of an object is altered, it creates Potential Energy. When you lift up up a yo-yo, its position is altered. It now has the ability (or potential) to do work. Almost every object has the potential to do work, or store energy, but the objects original position needs to be altered so it can eventually move. For example. If you pick the Yo-Yo up off the table, it now has altered its original position, and can store energy because it can now work with your help.

Position Examples: Wound-Up Spring Baseball Pitcher

Rubber Bands and a Target Potential Energy Rubber Bands and a Target The first form of energy is Potential energy. This is energy due to position.. Its also known as “stored energy.” To calculate PE you take the object’s weight and multiply it by the earths gravitational pull and the distance the object can fall. Here show students a rubber and and a target hanging on the wall. Demo and discuss what happens as the rubber band flies to the target.

More Examples of (Position) Potential Energy: Stretching a rubber band. -Stores energy Water at the top of a waterfall. -Stores energy Yo–Yo in held in your hand. -Stores energy because of position Some examples of potential energy are.. Stretching a rubber band… this store energy because it has the ability of doing work. Water at the top of the fall has the ability of falling, therefore it stores energy. A Yo Yo held in your hand stores energy because when you alter its position it now has the ability of doing work. A bow and arrow has stored energy because its position has changed and it now has the capability of shooting the arrow. Drawing a Bow. -Stores energy because of position

Chemistry Examples: Wood Coal Oil Gas Items that have stored energy.

How does “chemistry” create energy? Take that pile of wood. Let’s make a fire. So – How is this wood an example of potential energy?

How does chemistry create energy? Imagine you are next to that fire. You get warm and the logs change from wood to ash (it’s a chemical reaction - remember that?) But how does wood have potential energy? Wood has stored energy that is released when burned. What is stored energy called again? Stored energy = potential energy!!

Do you have more examples of potential energy? Write 2-3 more examples in your notes

An object has potential energy because of its position, shape, or chemistry

An object’s gravitational potential energy is increasing as it gets higher

The more mass an object has the more potential energy it has

Kinetic energy is energy of motion.

Examples Kinetic Energy

Swinging a Hammer Throwing a Ball Running

Weather

Rocks falling off a cliff or rolling down a hill Bowling Rocks falling off a cliff or rolling down a hill Kinetic energy of ball is transferred to pins

Falling or flowing water Car moving on a track of a roller coaster

Plate movement resulting in a earthquake

Release of energy through a volcanic eruption (gases, magma, ashes…)

Do you have more examples of kinetic energy?

The amount of kinetic energy an object has depends on its mass and speed

The faster the object goes, the more kinetic energy the object has

An object with a larger mass will have more kinetic energy than a smaller object at the same height

Examples both Potential and Kinetic energy

Potential Energy Converted to Kinetic Energy… When stored energy begins to move, the object now transfers from potential energy into kinetic energy. Potential energy eventually will need to transfer from it’s stored energy into motion. If a person is standing still, they obtain potential energy because the have the ability to walk or run… if the same person who is standing still decides to start running, then they have transferred their PE into KE… in other words, they went from storing energy, to moving energy. Standing still Running

As the potential energy increases, the kinetic energy decreases

As the potential energy decreases, the kinetic energy increases

Trampoline Potential energy when you are at top of bounce. Potential energy when trampoline is stretched down towards ground.

Avalanche

Waterfall

Pendulum Wrecking ball has potential energy. Hand has kinetic energy

http://www.teachersdomain.org/asset/mck05_int_rollercoaster/

Energy Skate Park http://phet.colorado.edu/en/simulation/energy-skate-park-basics

What is the relationship of potential and kinetic energy?

Potential and kinetic energy are inversely proportional (opposites)