unit 3 – energy! s8p2. students will be familiar with the forms and transformations of energy. a....

Unit 3 – Energy!S8P2. Students will be familiar with the forms and

transformations of energy.

a. Explain energy transformation in terms of the Law of Conservation of Energy.

b. Explain the relationship between potential and kinetic energy.

c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their

characteristics. d. Describe how heat can be transferred through matter by the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat

(convection)

Essential Question

How are ENERGY, WORK, and POWER related?

What is Energy? P.442• Discover Activity:

1. Hold a meter stick vertically with the zero end on the ground.

2. Drop a tennis ball from the 50-cm mark and record the height to which it bounces.

3. Drop the tennis ball from the 100-cm mark and record the height to which it bounces.

4. Predict how high the ball will bounce if dropped from the 75-cm mark. How did you make this prediction?

5. Test your prediction.6. Conclude – How does the height from which you drop

the ball relate to the height to which the ball bounces?

What is Energy? P.442• Work is done when a force moves an object

through a distance• The ability to do work or cause change is called

energy.• Work is the transfer of energy; work and energy

are measured in joules.• If the transfer of energy is work, then power is

the rate at which energy is transferred, or the amount of energy transferred in a unit of time.

Power = Energy transferredtime

• Power is involved whenever energy is being transferred.

Kinetic Energy• Moving objects do work, so they have energy.• The energy an object has due to its motion is called

kinetic energy.• Kinetic energy of an object depends on its mass and

its velocity – KE increases as mass increases. KE also increases as velocity increases.

• Recall the meanings of mass and velocity:Mass = A measure of how much matter is in an object.

Velocity – Speed in a given direction.

Calculating Kinetic EnergyKinetic energy = ½ x Mass x Velocity2

• Changing the velocity of an object will have a greater effect on its kinetic energy than changing its mass by the same factor because velocity is squared.

Potential Energy• Stored energy that results from the position or

shape of an object is called potential energy. • This type of energy has the potential to do work.

Let’s see an example of Kinetic and Potential Energy at work!

Gravitational Potential Energy • is related to an object’s

height, and is equal to the work done to lift it.

• The more an object weighs, or the greater the object’s height, the greater its GPE

GPE = Weight x Height

Elastic Potential Energy

• Is the potential energy associated with objects that can be stretched, or compressed.

Roadrunner Energy Video Link

Energy Skate Park

• Yes, even Bill loves to demonstrate Kinetic and Potential energy!

Bill Nye the Science Guy

Can You ANSWER the Essential Question?

How are ENERGY, WORK, and POWER related?

Essential Question:• Differentiate between kinetic

and potential energy.

Warm-Up: Venn Diagram

Gravitational Potential Energy

Elastic Potential Energy

Standard: S8P2c• Compare and contrast the

different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics.

Essential Question:• How are the different forms of

energy related?

Mechanical Energy• The form of

energy associated with the position and motion of an object

Mechanical Energy = Potential energy + Kinetic Energy

Thermal Energy• The total

potential and kinetic energy of the particles (atoms and molecules) in an object. Also called HEAT Energy!!!

Electrical Energy• The energy of

electric charges – can be a form of kinetic or potential depending on whether the charges are moving or stored.

Chemical Energy• Is potential energy

stored in the chemical bonds that hold chemical compounds together (food, matches, cells).

Nuclear Energy• Potential energy that is stored in

the nucleus of an atom; released during a nuclear reaction (fission, fusion)

Electromagnetic Energy• Energy that travels in

waves, having some electrical and some magnetic properties.

Also called Sound and Light/Radiant Energy!!!

Remember MR. CHEN• M-MECHANICAL ENERGY• R – RADIANT

(ELECTROMAGNETIC/LIGHT&SOUND)• C-CHEMICAL ENERGY• H-HEAT ENERGY (THERMAL)• E-ELECTRICAL ENERGY• N-NUCLEAR ENERGY

Essential Question:• How are different forms of

energy related?

Standard: S8P2a• Explain energy transformation in terms of

the Law of Conservation of Energy.

• OPEN YOUR TEXTBOOK TO

P.454!!!!!!

Energy Transformation• A change from one form of energy

to anotherSingle Transformations – One form of energy needs to be transformed into another to get work done. Ex: Toaster transforms electrical energy to thermal energy to toast your bread.

Multiple Transformations – A series of energy transformations is needed to do work. Ex: Mechanical energy used to strike a match is transformed to thermal energy, releasing stored chemical energy, which is transformed to thermal energy and electromagnetic energy.

Transformations Between Potential and Kinetic Energy

• Demonstration

Law of Conservation of Energy

• When one form of energy is transformed to another, no energy is destroyed in the process. Energy cannot be created or destroyed.

Friction transforms mechanical energy to thermal energy!

Roller Coaster Activity Instructions

• Watch this video first!• Now read the instructions on the worksheet

that your teacher gives you.

Einstein’s Theory of Relativity• Einstein theorized that matter can be

transformed to energy because destroying just a small amount of matter releases a huge amount of energy. He MAY be wrong according to recent research...!!!

• In some situations, energy alone is not conserved; however, since matter can be transformed to energy, scientists say matter and energy together are always conserved.