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Learning Intentions, key questions:
Energy Learning Intentions, key questions: What is Energy? Why is Energy so important? How can we measure and quantify Energy? How do living things obtain Energy? How does society obtain Energy? Task: write down 10 facts you know about Energy
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The currency of the Universe and human kind....
Energy! The currency of the Universe and human kind....
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What is Energy?? What is happening here?
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Lisa is doing work by cranking the generator.
She puts energy from her body into the generator.
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Cranking the generator converts Lisa’s work into electric energy
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The electric energy is then converted into light energy and heat in the light bulb.
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Lisa gets her energy that enables her to do work from her food.
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The light energy is going out and is absorbed somewhere.
Light delivers its energy in form of some heat where it ends.
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Energy is converted from stored chemical energy in the food
into work, electric energy, light energy and finally heat.
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But that is not where the story of Lisa’s energy starts.....
In fact it started....
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14 billion years ago with the big bang!
Are fused in the Sun into Helium, loosing lots of Energy to Radiation Hydrogen, Protons from the big bang Big Bang Radiation from nuclear fusion Sunlight Energy converted into Carbohydrates Energy stored in Carbohydrates, Proteins, Fats
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Where do we find energy and how is it called?
Potential Energy Chemical potential energy Kinetic Energy Potential Energy Kinetic Energy Chemical Energy Kinetic Energy Thermal Energy Electric Energy
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Quantifying Energy Moving something against a force of 1 Newton over a distance of 1 meter requires the energy of 1 Joules. Mass of 100g 100g Lifting 100g by 1 Metre = 1 Joules of energy Gravitational Force of ~ 1 Newton 100g Earth Surface
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Quantifying Energy After lifting a mass of 100g against the Earth gravitational force by 1m it has now 1 Joules of stored potential energy. After the 100g has been lifted by 1m it now has 1 Joules of stored potential Energy 100g Lifting 100g by 1 Metre = 1 Joules of energy Earth Surface
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Quantifying Energy Dropping the 100g mass from 1 m the force of Gravity accelerates the mass. It converts its potential energy into kinetic (moving) energy. When the 100g mass is dropped from 1m it accelerates. It converts its potential energy into kinetic energy 100g Earth Surface
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Power: Converting Energy Fast!
Doing work of 1 Joules every second (per second) is a Power of 1 Watt. Lisa is working with a Power of 1 Watt. 100g 100g 100g 100g 100g 100g 100g 100g Lifting 100g by 1 Metre = 1 Joules of energy 100g Earth Surface
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Power: Spending Energy Fast!
Doing work of 100 Joules every second (per second) is a power of 100 Watt. Now Lisa is working with a Power of 100 Watt. 1kg 1kg 1kg 1kg 1kg 1kg 1kg 1kg Lifting 1kg by 1 Metre = 100 Joules of energy 1kg Earth Surface
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Lisa has to do work with a power of 100 Watt to make a 100 Watt light bulb glow
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In fact, she needs to work with a power of over 100 Watt to make up for losses
100 Watt light bulb Energy Losses, heat, friction
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Summary Energy is measured in Joules
Moving for 1 meter against a force of 1 Newton requires 1 Joule of Energy. Energy is never created or destroyed, but it can be converted. Energy can be concentrated or diluted. Naturally, Energy is trying to get more and more diluted. Power is the rate of Energy conversion. Converting 1 Joule of Energy per second is a power of 1 Watt.
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Quiz 1 Which statements are correct: Energy can...
Be created but not destroyed Be destroyed but not created Not be created and not be destroyed Only be created in power stations Can be concentrated or diluted. Can be stored Nature tends to dilute energy over time
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Quiz 2 Which can be energy sources? Hamburger Sun Electric Kettle Coal
Block of Ice Firewood Waterfall Light bulb All of the above
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Quiz 3 Can you name all the stages of energy conversion involved in making the light bulb glow?
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Quiz 4 Which statements are correct? Energy is measured in Watt.
Energy is measured in Joules. 1 Joules = lifting 100g by one meter. 1 Watt = lifting 1kg by one meter. Power is measured in Watt. 1 Watt = 1 Joules of energy converted per second.
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Energy in Food Key Questions:
How much Energy is in our food? How much Energy do we need to live each day? How much of this can we use to do useful work?
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How much Energy do we eat per day?
Humans eat daily 10,000 kJ or 10,000,000 J 1 kJ = 1000 J (kilo Joule) 1 Cheeseburger + medium chips ~ 2500 kJ
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How much Energy do we eat per day?
Humans eat daily 10,000 kJ or 10,000,000 J 1 kJ = 1000 J (kilo Joule) Average daily human food intake is 10,000 kJ 4 x ( Cheeseburger + medium chips ) ~ 10,000 kJ
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How much Energy do we eat per day?
4 x ( Cheeseburger + medium chips ) ~ 10,000 kJ A day has: 24 h x 60 min x 60 = 86,400 seconds 10,000 kJ per day = 10,000 kJ / 86,400 seconds = 115 Watt of continuous power!
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Can Lisa work with 115 Watt? She can for a short time!
Lisa needs most of her energy to stay alive and warm!
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Human Energy use Food Intake: Energy use
10,000 kJ/Day 115 Watt average Energy use Body functions, heat, thinking, heart, 100 Watt Energy use Storing some food energy for emergencies Food Store: Weeks worth of fat and other carbohydrates. Energy use Work, some, but on average no more than 25 Watt continuous
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Human Energy use Heat emission of about 100 Watt is the biggest constant energy loss of humans
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Carbon Compounds as Energy Carrier
Human and Animal energy is derived from energy rich food - Carbohydrates, which are made in plants from CO2, Water and solar energy. Civilisation has found fossil energy, huge stores of Carbohydrates made by solar energy and laid down over hundreds of millions of years in geological deposits.
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The natural flow of Energy available to life on Earth
Energy is handed from plants to animals via the Cycle of Carbon Compounds. The Carbon-Cycle CO2 CO2 Sun, nuclear fusion H2O CxHx CxHx CxHx Sunlight Energy converted in Carbohydrates Energy stored in Carbohydrates, Proteins, Fats
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The industrial flow of Energy available to civilisation
CO2 CO2 CO2 CO2 CO2 CO2 Sun, nuclear fusion CxHx CxHx CxHx CxHx CxHx Millions of years of dead plant and animal matter CxHx Coal
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