Grade 9 Tech. Module

Energy and Power

Introduction

Energy and power technology refers to systems that convert energy from one form to another to perform useful tasks.

The system may: • convert chemical energy into heat energy (ie. a

propane fireplace)

• convert mechanical energy into electrical energy (ie. windmill),

• or convert radiant energy into electricity (ie. photovoltaic cell). Can you name some others?

Introduction

• Unit 1 - Big Ideas

• Unit 2 - Basic Skills

• Unit 3 - Design Activity

Grade 9 Tech. Module

Unit 1-Big Ideas

Introduction The purpose of the big ideas section is to provide students with

an introduction to the ideas, terminology and concepts covered in the module.

• Topic 1: Mass and Force

• Topic 2: Work Energy and Power

• Topic 3: Sources Forms Conversion and Transmission of Energy

• Topic 4: Sources of Energy for Electrical Generation

• Topic 5: Career Connections

Topic 1: Mass and Force Mass is a measure of the amount of matter in an object and is

measured in kilograms (Kg).

What is matter?

As you already know, everything is made up of atoms. Atoms are constructed from neutrons, protons, and electrons.

The mass of an atom is determined by the number of neutrons and protons that make up the atom.

Iron atoms have a lot of mass, and consequently the anvil has a

lot of mass.

A force is the measurement of influences that change the direction of an object.

Basically “a push or pull exerted on an object”.

• Who is pushing? Who is pulling?

• Watch the Video: Push and Pull

There are many other types of forces: buoyant, magnetic, electrostatic, gravitational, elastic, and frictional.

• Look at the pictures below. Identify the type of force shown in each picture. (click on the picture)

Buoyant Magnetic Gravity and Friction

Electrostatic Elastic Friction

Measuring Force

The standard unit of force is the Newton (N). Named after Isaac Newton

Measuring Force

1 N is approximately the same as the amount of gravitational force the Earth exerts on an object with a mass of 100 grams (ex. An Orange) (1 N = 100 g).

Try it :

• Use a spring scale to demonstrate 1 Newton of force.

• Estimate the approximate force required to support objects of varying masses.

Activity

C lick Here

Forces in action Forces and motion

• What factors effect the gravitational force experience between two objects?

Gravity

Gravity

Gravity is the force of attraction between two objects having mass.

Gravitational force is denoted by the symbol g. Gravitational force at sea level on earth is 9.8 newtons per 1 kg of mass.

All object fall at the same rate!

See „ Falling objects file‟

All objects fall at the same rate!

See „ Falling objects file‟

• The amount of gravitational force between two objects is related to the mass of the objects and the distance separating them.

The weight (N) of an object is merely a measure of gravity.

• The more massive a body is the stronger its gravitational force.

Mass is a measurement of the amount of

matter something contains, Weight is the measurement of the pull of

gravity on an object.

How are weight and mass different?

How are weight and mass different?

Mass is measured by using a balance scale. Weight is measured on a spring scale.

How are weight and mass different?

The Mass of an object doesn't change when an object's location changes. Weight, on the other hand does change with location

The anvil is shown in three locations. In each location, its mass is the same. but its weight is very different.

Mrs. Mini Me weighs 100 Newtons on Earth. During a recent galactic holiday she traveled to several different planets. Wishing to maintain her weight, she was careful not to overeat. Each day as she weighed herself she was astonished to discover her amazing weight gain. Can you explain what happened?

Eeek!

Whee!

Earth Jupiter Mars

Mass: 10kg Mass: 10kg Mass: 10kg

Activity

Check it out: • http://www.exploratorium.edu/ronh/weight/ • Or Web file: Calculating weight

• Videos: - Magic School Bus – No Gravity (26mins)

– Weight Introduction (3 mins) – Weight vs mass (2 videos) – Gravity and Mass (2 mins)

Topic 1 Activity: Poster design

Create a poster that would illustrate one or all of the following concepts reviewed in this Topic.

ie: mass, force, gravity, or weight.

Topic 2: Work, Energy and Power Work occurs when energy gets transferred from one object to

another object.

The standard unit of work is the Joule (abbreviated J).

One Joule is equivalent to one Newton of force causing a movement of one meter.

1 Meter

1 Newton

Also we may consider: One joule as the amount of energy required to lift a 1 newton of weight a distance of 1 meter.

Three Conditions for work to occur:

In order to do work, a force has to be applied to a mass and

the mass has to be moved in the direction of the force over

a distance.

Can you determine if work was done in the following?

• Throwing a ball

• Lifting a book from the floor to a table

• Lifting a book from a table to the floor

• A waiter caring a tray of food

ENERGY Energy is the ability to do work. (that is to make something move) Since energy is the ability to do work, it is also measured in

Joules. Example, a plane uses energy to carry passengers.

When electricity turns a motor, the motor is using energy to make the blade move.

When water is changed into steam it uses energy to move the train.

A piece of buttered toast contains about 315 kilojoules (315,000 joules) of energy. With that energy you could:

- Jog for 6 minutes

- Bicycle for 10 minutes

- Walk briskly for 15 minutes

- Sleep for 1-1/2 hours

- Run a car for 7 seconds at 80 kilometers per hour

- Light a 60-watt light bulb for 1-1/2 hours

- lift a sack of sugar from the floor to the counter 21,000 times!

There are Two types of Energy

1. Kinetic Energy

Kinetic energy is energy of a mass in motion.

An example of kinetic energy would be a loaded oil tanker coming up Placentia Bay. This vessel would need miles to stop simply because it has a tremendous amount of kinetic energy.

The energy of the wind and motion of the turbine blades has been used for centuries to pump water or to drive millwheels to grind grain.

2. Potential energy

Potential Energy (PE) is Stored Energy. There are many ways to store energy,

each resulting in a different name for potential energy.

For example, the energy stored in the large weight of a pile driver can force a post into the ground when it falls.

More examples of potential energy would be

- sunlight, coal, or oil being pumped out of Hibernia

- water in a dam above a power plant, etc.

Power

Power is the amount of energy expended in a unit of

time or the amount of work done in a unit of time.

The unit of power is the Watt which is a Joule per second.

Power Example, shoveling a mound of snow by hand may

take all day whereas a loader can come in and do that in a few minutes.

The loader does the same amount of work in a shorter period of time and therefore has more power.

Small Power

Large Power

Power

1 Watt is defined as 1 joule of energy expended in 1

second.

Since energy applied over a distance is work done on the object,

1 watt of power = 1 joule of work completed in 1 second

• Sometimes, work is done very quickly and other

times work is done rather slowly.

Video - Energy 55 mins

Activity: Bottle Rockets Handout:

Activity

Electric current: is the movement of electrons from a negative

terminal back to the positive terminal of a battery .

Electric Current

Electric Current

Electrons flow from regions of high Potential Energy to

regions of low Potential Energy (something like the pile

driver falling in the Potential Energy slide earlier)

In the diagram electrons loose energy because of friction in the

wires and the filament of the lamp.

Another name for these obstacles is resistance.

In the battery energy comes from the chemical energy in the battery

which "pumps them up to the top of the hill (casing of battery).

Current

Units: C/s or Amperes, A

Current is the rate at which the electric charges move through the

conductor and is given the symbol (I).

MEASURING CURRENT

Current is measured with an instrument called an ammeter.

• An ammeter typically has a red terminal and a black terminal. Connect the red terminal to the positive terminal of the battery.

Electric Potential Difference (VOLTAGE)

Charge does not flow on its own.

To produce an electric current, a difference in potential Energy is

required.

Electric Potential Difference (VOLTAGE)

This electric potential difference is called electromotive force or Voltage.

In the automotive battery shown below, the EMF is the total charge

between the two terminals.

Simply put, this means that 1 volt of EMF means there are 6.24 X 1018 electrons available to do work.

Sources of Potential Difference (Voltage)

What is Voltage? Confused??

Whatever the source, it helps to picture potential difference or voltage as the

force behind the current--the force making the electrons move.

Voltage may be viewed as a hill: the

steeper the hill, the faster a bike will roll

down. The "current of bikes" will deliver

more bikes to the bottom of the hill faster

when the hill is steep.

Likewise, when voltage is high, it seems

reasonable to predict that a larger current of

electrons will roll through the circuit.

MEASURING VOLTAGE

The instrument used to measure voltage is called a voltmeter.

A voltmeter can measure the increase in potential at the terminals of the

dry cell, and the decrease in potential as the electrons give up their

energy in the lamp.

Voltmeters must be hooked up in parallel

Unlike the ammeter the circuit is not broken to connect a voltmeter.

• The red terminal of the voltmeter is connected to the positive terminal of

the cell. (However, the red terminal of the voltmeter must be connected to

the terminal of the bulb that is towards the positive terminal of the dry cell.)

• Voltmeters must have an extremely large resistance to discourage

electrons from passing through them.

Current Voltage

Measured in Amps, A Volts, V

Measured with Ammeter in series

Voltmeter in parallel

Circuit symbol of measuring devise

Confused?? Look at it this way: The Mouse Cheese Analogy

Negative charges are attracted to positive charges the same way mice

are attracted to cheese. The negative charges (mice) will gladly do work

in order to get to the positive charges (cheese).

Voltage:

The amount of work that each charge (mouse) will do as it goes through

the circuit. Can also be thought of as the amount of push on the

charges or how hungry the mice are.

Current:

The number of charges (mice) passing a point per second. The rate of

flow of charges.

Resistance:

The opposition to the flow of charge. Any appliance that asks the

charge (mouse) to do work will slow it down.

The Mouse Cheese Battery (cell)

The battery goes "dead" when all the negative charges make it through

the circuit and get to the positive charges.

Forms of Energy

Remember there are Two types of Energy: Potential and Kinetic.

Can you identify some various sources of energy?

Chemical Energy (Potential)

Chemical energy is the energy stored in the bonds of atoms and

molecules.

Biomass, petroleum, natural gas, propane, batteries, and coal are

examples of stored chemical energy.

Chemical Energy (Potential)

Chemical energy is the energy stored in the bonds of atoms and

molecules.

Nuclear Energy (Potential)

Nuclear energy is the energy stored in the nucleus of an atom - the

energy that holds the nucleus together.

The nucleus of a uranium atom is an example of nuclear energy.

Stored mechanical energy (Potential)

Stored mechanical energy is energy stored in objects by the

application of a force.

Compressed springs and stretched rubber bands are examples of

stored mechanical energy.

Gravitational Energy (Potential)

Gravitational energy is the energy of place or position.

Water in a reservoir behind a hydropower dam is an example of gravitational potential energy. When the water is released to spin the turbines, it becomes motion energy.

Generating Electricity

Motion Energy (Kinetic)

The movement of objects from one place to another is motion.

Wind and hydropower are examples of motion.

Radiant Energy (Kinetic)

Radiant energy is electromagnetic energy that travels in transverse

waves.

Radiant energy includes visible light, x-rays, gamma rays and radio

waves. Solar energy is an example of radiant energy.

Thermal Energy (Kinetic)

Thermal energy (or heat) is the internal energy in substances - the

vibration and movement of atoms and molecules within substances.

Geothermal energy is an example of thermal energy.

Sound Energy (Kinetic)

Sound is the movement of energy through substances in longitudinal

(compression/ rarefaction) waves.

Electrical Energy (Kinetic)

Electrical energy is the movement of electrons.

Lightning and electricity are examples of electrical energy.

Video - Energy Sources 6 mins Handout: Forms of Energy

Converting Energy

Energy can be converted from one form to another. There are many

methods that can be used.

Look at the following examples and determine which type of energy

conversions occurred.

Turn a flashlight on

A tree growing Pouring water into a glass

Rubbing two sticks together to start a fire Using a magnifying glass to ignite a piece of paper Video: Transformation of Energy - 4 mins

“Show and Tell”

Many technological devices are designed to convert energy from one

form to a form suitable for a given purpose.

Next day, bring a device to class for discussion that converts energy.

Research Assignment

Electricity can be produced in a number of ways:

• Turbines in nuclear plants

• Hydroelectric stations

• Fossil fuels

• Solar panels/collectors

• Windmills

• Batteries

• Hydrogen cells

Select an example of an electricity source and create a pamphlet

(Microsoft Publisher) explaining the system that produces the electricity.

Electricity is carried in overhead wires with very high voltages

between communities. The reason for this is to reduce energy loss

(the higher the voltage the less energy loss over long distance).

In a coal plant there are four main stages:

1. the fuel is burned to boil water to make steam

2. the steam makes a turbine spin

3. the spinning turbine turns a generator which produces electricity

4. the electricity goes to the transformers to produce the correct voltage

.

220 000 V

240 V

The future: WiTricity

Imagine a future in which wireless electricity makes everyday products more convenient, reliable, and environmentally

friendly.

WiTricity Corp. harnesses highly resonant magnetic coupling to transfer

power over distances ranging from centimeters—to several meters.

The future: Solar Power Satellites

One suggestion for energy in the future is to put huge solar power

satellites into orbit around the earth. They would collect solar energy from

the sun, convert it to electricity and beam it to Earth as microwaves or

some other form of transmission

Legal, Ethical and Environmental Impacts

Every kind of generation, conversion, and transmission of energy has some legal, ethical, and environmental issue related to it.

Can you name some common problems associated with the various types of Energy Sources we discussed?

Examples

Wind farms in western Canada are affecting: • wildlife (rare species of bats, birds), • humans (low frequency noise damage), and aesthetics. • Ice buildup on blades during winter months can fly off and cause property damage or injury. • Communities can be displaced • and natural vegetation can be destroyed..

Examples

Hydroelectric reservoirs cause rotting vegetation which produces significant amounts of green house gases. In some cases the destruction of sacred native lands have caused disputes with native cultures (Three Gorges Dam, China, James Bay Project, Quebec).

Examples

Geothermal energy can cause noise pollution, dissolved solids in steam quickly erode pipes, natural steams contain many green house gases, not easily transported.

Activity: Extra Extra! There are many new technologies that are evolving for more efficient

conversion, transmission, and consumption of electrical energy Some examples: • Transmission issues and the re-emergence of interest in DC power

• Consumption issues and hybrid vehicles

• Miniaturizing of electronic circuitry

• Quantum computers

• The introduction of fluorescent and LED technologies

• Conversion advances with photovoltaic solar cells, wind, small hydro, and biomass technologies

Research an emerging technologies and develop a Newspaper advertisement to sell your product.

Activity: Extra Extra!

How is energy generated? How much does it cost? How does it affect the environment? You will be given complete control over a small town. You need to balance your city‟s growth with its environmental impact to build the best city possible..

Visit the website: Energy story http://www.energyquest.ca.gov/story/index.html Browse the site and try the different activities available.

Also try: http://go.ucsusa.org/game/

http://www.myfootprint.org/

Handout: Review sheet - Unit 1