Unit B – Energy Transformations

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# Unit B – Energy Transformations - PowerPoint PPT Presentation

Unit B – Energy Transformations. Chapter 5 – Energy Transformations. In this chapter you will learn: how to identify different types of energy that some energy conversions absorb energy and some release it how energy is converted and that energy is lost with each conversion

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### Unit B – Energy Transformations

Chapter 5 – Energy Transformations
• In this chapter you will learn:
• how to identify different types of energy
• that some energy conversions absorb energy and some release it
• how energy is converted and that energy is lost with each conversion
• about the law of conservation of energy
5.1 - Energy
• Energy is the ability to do work
• Energy causes changes in:
• temperature
• direction of motion
• speed
• shape
Two Types of Energy
• Potential Energy is stored energy
• Examples:
• chemical energy stored in the food you eat
• gravitational potential energy when you are at the top of a hill
• Kinetic Energy is energy due to motion
• Examples:
• the flow of electrons (electricity)
• skiing down a mountainside
5.2 – Many Forms of Energy
• Energy on the Earth originates as solar energy from the Sun
• Energy from the Sun is converted by plants:

solar  chemical  kinetic

(photosynthesis) (cellular respiration)

Energy from the Sun is converted by wind turbines:

solar  wind  electricity

• Energy from the Sun is converted by solar panels:

solar  electricity

5.3 – Understanding Energy Conversions
• Energy must get converted so that it is useful
• Energy entering a system is called input energy
• System that changes the system is called the converter
• Energy leaving the system is called the output energy

When energy is converted from one form to another, thermal energy is produced

• Sometimes heat energy is useful:
• ie. heat released during cellular respiration heats your body
• ie. chemical reaction in a “hot pack”
• When the thermal energy is not useful, it is called waste energy:
• ie. heat from a light bulb
• ie. heat from a car engine
5.4 – Conservation of Energy
• Whenever energy is converted by a device, the amount of energy coming out is equal to the amount of energy coming in

What types of energy are produced by a blow dryer?

• Thermal energy provides the heat to dry
• Kinetic energy in the moving air
• Some electricity is converted to sound energy
• The glowing elements produce light energy
• Friction produces thermal energy that is not used to dry your hair.
5.5 – Energy Conversion Systems
• Some output energy produced during an energy conversion is useful (useful output energy) and some output energy is not (waste output energy)

No energy conversion is 100% efficient

• When energy is converted from one form to another, thermal waste energy will always be produced.
Pages 98 - 113

### Chapter 6 – Electric Energy at Home

Chapter 6 – Electrical Energy at Home
• In this chapter you will learn :
• about technologies that various forms of energy into electricity
• how appliances convert electricity into other forms of energy
• how to calculate the efficiency of electrical devices
• how to measure electricity and calculate power
• why it is important to conserve energy
6.1 – Generating Electrical energy
• In the early 1800s, Michael Faraday discovered that moving a magnet through a coil of copper wire generated an electrical current
• Faraday used these observations to make the first electric generator

A generator is a device that makes electricity

• Most electric energy is made in a generator
• A generator consists of A magnet and a coil of wire.

Electrical current can be increased by:

• Increasing the number of coils
• Using a stronger magnet
• Moving the magnet/ wire faster

Energy conversion in a generator:

• Not all of the kinetic energy is converted into electrical energy. If energy is conserved during a conversion, what happened to the rest of the kinetic energy?
Chapter 6.2 – Generating and Distributing Electric Energy

Turbines and Generators

• Generators contain one or more turbines

In order to make electricity, turbines need to be connected to a generator.

• As the blades of the turbine turn, their kinetic energy is transformed into kinetic energy in the generator.
• Kinetic energy in the generator is transformed

into electrical energy

kinetic  electrical

Power Generating Plants
• Hydro-electric, thermo-electric, and thermonuclear plants all use turbines and generators to produce electricity.
Coal-fired Thermo-electric Generation
• Coal in Alberta is cheap and plentiful
• Emissions pass through a “scrubber” to remove some of the harmful chemicals from the smoke
How it works:
• Coal is pulverized and combusted
• Thermal energy from burning coal converts water to steam
• High-pressure steam causes turbine blades to turn
• The spinning turbine turns the generator, producing an electric current
• The steam leaves the turbine and enters a cooling chamber before returning to the furnace.
Hydro-electric Plant
• The kinetic energy of falling water is used to produce electricity
Hydro-electric generation
• What are some possible advantages and disadvantages to using hydro-electric power?
Thermonuclear Power Plant
• Uranium atoms are split by nuclear fission to release large amounts of thermal energy.
• Thermal energy makes steam.
• Steam is used to turn turbines, producing electricity.

What are some of the advantages and disadvantages of producing electricity with nuclear energy?

Japan Nuclear Reactor Explanation

Distributing Power - The Power Grid
• Electrical generating plants are often located far away from communities.
• Electricity must be transmitted hundreds of kilometers along power lines.
• About 10% of energy is wasted as thermal energy as it moves along the power lines.
• Constructing power plants close to communities creates environmental concerns.
6.3 – Electrical Energy and Power
• We can measure how fast energy is transferred from one object to another; how fast work is done
• Power is a measure of the rate of energy transfer

The formula used to calculate power is:

power is measured in Watts (W)

energy is measured in Joules (J)

time is measured in seconds (s)

• A generator produces 2 J of energy every second. How many watts of power does it produce?

An aquarium light bulb uses 7 J of electric energy in one second. How many watts of power does it consume in 3 seconds?

Speakers on a computer use 40 J of electric energy. How many watts of power do the speakers consume in one minute (60 seconds)?

You can calculate how much electric energy is consumed by a device by re-arranging the formula:

• The formula used to calculate how much energy is used is:

Where energy is measured in watt hours (Wh)

power is measured in watts (W)

time is measured in hours (h)

How much electric energy does a 60 W light bulb use if it is left on for 2 hours?

• How much electric energy does a 240 W fan use if it is left on for 1.5 hours?
6.4 – Efficiency and Saving Energy
• Some devices are better than others at converting electrical energy into useful output energy
• Which of these devices is more efficient at converting electricity into light? How do you know?
Energy Efficient Light Bulbs…

NatGeo energy efficient bulbs

Device efficiency is expressed as a percentage (%)

• To determine the efficiency of a device:
• An incandescent light bulb converts 200 J of electricity into 25J of light. What is the efficiency of the bulb?

An electric kettle uses 240 000J to heat water. 196 000J is actually used to heat the water. What is the efficiency of the kettle?

Using energy efficient devices will benefit:

• Electrical bills by saving money
• Environmental by using fewer fossil fuels
Chapter 7.1 – Energy for Life
• Plants convert the Sun’s solar into chemical potential energy stored in glucose (sugar)
• This is done through the process of photosynthesis

solar  chemical potential

Animals convert the chemical potential energy in plant and animal cells into mechanical energy

• This is done through the process of cellular respiration

chemical potential  mechanical

• Energy stored in the cells of plants and animals is transferred through the food chain

Only 10% of energy is transferred to the next level as it moves through an food chain

• This is demonstrated by an energy pyramid
• Less and less energy is available at each level in a food chain
• Fewer organisms can

be supported with

each level

7.2 – The Need for Energy
• Our bodies area able to maintain a constant temperature through the process of homeostasis
• If your body temperature drops:
• Shivering burns sugar and produces heat
• Blood is sent to core of the body to preserve heat
• If your body temperature rises:
• Blood is sent to skin to release extra heat to air
• Perspiration transfers heat energy to the air

The rate at which the body uses energy is called metabolism

• A person with a high metabolism:
• has high energy needs
• converts a lot of chemical energy into heat energy
• A person with a low metabolism has low energy needs
• has low energy needs
7.3 – Sources of Energy
• The main source of energy for humans is glucose, a simple carbohydrate
• Glucose that is not immediately used by the body may be converted into glycogen for short term storage
• Glycogen can be easily turned back into glucose
• Glycogen that is not used is converted into fat for long-term storage

When your body needs to access energy:

• Glucose is immediately used
• Glycogen is converted into glucose
• Fat may be converted back into glucose
• Muscle protein is converted into glucose

If all energy reserves have been depleted:

• Body will begin to convert muscle protein into energy
• This occurs in cases of extreme malnutrition
• Long term malnutrition results in permanent damage to body organs and structures
7.4 – Human Energy Needs Change
• An individual’s metabolic rate depends on:
• Age – developing babies and young children have a faster metabolism than adults
• Time of day – metabolism is highest in the morning
• Exercise – activity raises metabolism
• Fitness level – large amounts of energy are required to stay in shape
8.1 – What are Fossil Fuels?
• Fossil fuels are formed over millions of years from the remains of once living organisms
• We can use the chemical potential energy that has been stored in fossil fuels
• Common fossil fuels:
• Coal
• Crude oil
• Natural gas

Fossil Fuels:

• are formed from the remains of one living organisms
• require heat, pressure, and a long time to form
• contains large amounts of chemical potential energy

How fossil fuels form

8.2 – Extracting Coal and Oil
• Fossil fuels must be removed from the ground before they can be of use
• Coal is quarried or mined, depending on depth
• A seismic survey uses shockwaves to locate potential locations for oil

Locating Petroleum

Distillation

• Crude oil is oil that is extracted from the ground
• Crude oil is refined into different products like:
• gasoline
• tar
• motor oil
• products are separated based on different boiling points
8.3 - Combustion
• Energy stored in fossil fuels is released during combustion
• chemical potential  thermal

All fossil fuels are hydrocarbons

• They are made up of hydrogen and carbon
• When hydrocarbons are combusted they release large amounts of heat and light energy

CH4 + O2 CO2 + H2O + energy

• When fossil fuels are combusted, CO2 and H2O are always produced
• How is the process of cellular respiration similar to combusting a fossil fuel?

Both cellular respiration and the burning of fossil fuels use hydrocarbons as a fuel source

• Both reaction require oxygen
• Both reactions produce CO2 and H2O
8.4 – The Other Side of the Coin
• Because fossil fuels take millions of years to form, they are non-renewable
• As global populations continue to increase, more people are competing for less oil
• How is this cartoon related to oil?

The combustion of fossil fuels releases large amounts of CO2 into the atmosphere

• Excess CO2 in the atmosphere is believed to increase Earth’s natural “greenhouse effect”