Модуль 1 - Общие сведения, глаголы to be, to have, конструкция there is(are), времена группы Indefinite Active Voice (1096805), страница 9
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We will look at the energy that makes our world work. Energy is animportant part of our daily lives.The forms of energy we will look at include:• Electricity• Biomass Energy - energy from plants• Geothermal Energy• Fossil Fuels - Coal, Oil and Natural Gas• Hydro Power and Ocean Energy• Nuclear Energy• Solar Energy• Wind Energy• Transportation EnergyWe will also look at turbines and generators, at what electricity is, how energy is sent to users, and how wecan decrease or conserve the energy we use.
Finally, we'll look at the "newer" forms of energy... and take alook at energy in the future.Energy causes things to happen around us. Look out the window.During the day, the sun gives out light and heat energy. At night, street lamps use electrical energy to lightour way.When a car drives by, it is being powered by gasoline, a type of stored energy.The food we eat contains energy. We use that energy to work and play.Energy can be found in a number of different forms. It can be chemical energy, electrical energy, heat(thermal energy), light (radiant energy), mechanical energy, and nuclear energy.Stored and Moving EnergyEnergy makes everything happen and can be divided into two types:• Stored energy is called potential energy.• Moving energy is called kinetic energy.With a pencil, try this example to know the two types of energy.Put the pencil at the edge of the desk and push it off to the floor.
The moving pencil uses kinetic energy.Now, pick up the pencil and put it back on the desk. You used your own energy to lift and move the pencil.Moving it higher than the floor adds energy to it. As it rests on the desk, the pencil has potential energy.The higher it is, the further it could fall. That means the pencil has more potential energy.How Do We Measure Energy?Energy is measured in many ways.One of the basic measuring blocks is called a Btu. This stands for British thermal unit and was invented by,of course, the English.Btu is the amount of heat energy it takes to raise the temperature of one pound of water by one degreeFahrenheit, at sea level.39One Btu equals about one blue-tip kitchen match.One thousand Btus roughly equals: One average candy bar or 4/5 of a peanut butter and jelly sandwich.It takes about 2,000 Btus to make a pot of coffee.Energy also can be measured in joules.
Joules sounds exactly like the word jewels, as in diamonds andemeralds. A thousand joules is equal to a British thermal unit.1,000 joules = 1 BtuSo, it would take 2 million joules to make a pot of coffee.The term "joule" is named after an English scientist James Prescott Joule who lived from 1818 to 1889.He discovered that heat is a type of energy.One joule is the amount of energy needed to lift something weighing one pound to a height of nine inches.So, if you lifted a five-pound sack of sugar from the floor to the top of a counter (27 inches), you woulduse about 15 joules of energy.Around the world, scientists measure energy in joules rather than Btus. It's much like people around theworld using the metric system of meters and kilograms, instead of the English system of feet and pounds.Like in the metric system, you can have kilojoules — "kilo" means 1,000.1,000 joules = 1 kilojoule = 1 BtuA piece of buttered toast contains about 315 kilojoules (315,000 joules) of energy.
With that energy youcould:•••••••Jog for 6 minutesBicycle for 10 minutesWalk briskly for 15 minutesSleep for 1-1/2 hoursRun a car for 7 seconds at 80 kilometers per hour (about 50 miles per hour)Light a 60-watt light bulb for 1-1/2 hoursOr lift that sack of sugar from the floor to the counter 21,000 times!Changing EnergyEnergy can be transformed into another sort of energy. But it cannot be created AND it cannot bedestroyed.
Energy has always existed in one form or another.Here are some changes in energy from one form to another.Stored energy in a flashlight's batteries becomes light energy when the flashlight is turned on.Food is stored energy. It is stored as a chemical with potential energy. When your body uses that storedenergy to do work, it becomes kinetic energy.If you overeat, the energy in food is not "burned" but is stored as potential energy in fat cells.When you talk on the phone, your voice is transformed into electrical energy, which passes over wires (oris transmitted through the air). The phone on the other end changes the electrical energy into sound energythrough the speaker.A car uses stored chemical energy in gasoline to move. The engine changes the chemical energy into heatand kinetic energy to power the car.A toaster changes electrical energy into heat and light energy.
(If you look into the toaster, you'll see theglowing wires.)A television changes electrical energy into light and sound energy.40Food EnergyEnergy changes form at each step in the food chain. Take an ear of corn as an example.Sunlight is taken in by the leaves on the corn stalk and transformed through photosynthesis.
The planttakes in sunlight and combines it with carbon dioxide from the air and water and minerals from the ground.The plant grows tall and creates the ears of corn - its seeds. The energy of the sunlight is stored in theleaves and inside the corn kernels. The corn kernels are full of energy stored as sugars and starch.
The cornis harvested and is fed to chickens and other animals. The chickens use the stored energy in the corn on thecob to grow and to move. Some energy is stored in the animal in its muscle tissue (protein) and in the fat.The chicken reaches maturity, a farmer slaughters it and prepares it to be sold. It's transported to thegrocery store. Your parents buy the chicken at the supermarket, bring it home and cook it (using energy).You then eat the chicken's meat and fat and convert that stored energy into energy in your own body.Maybe you ate the chicken at a picnic.
Then you went and played baseball. You're using the energy fromthat chicken to swing the bat, run the bases and throw the ball.As your body uses the energy from the chicken, you breathe in oxygen and exhale carbon dioxide. Thatcarbon dioxide is then used by other plants to grow.So, it's a big circle!Heat EnergyHeat is a form of energy. We use it for a lot of things, like warming our homes and cooking our food.Heat energy moves in three ways:1. Conduction2. Convection3. RadiationConduction occurs when energy is passed directly from one item to another.
If you stirred a pan of soup onthe stove with a metal spoon, the spoon will heat up. The heat is being conducted from the hot area of thesoup to the colder area of spoon.Metals are excellent conductors of heat energy. Wood orplastics are not. These "bad" conductors are calledinsulators. That's why a pan is usually made of metal whilethe handle is made of a strong plastic.Convection is the movement of gases or liquids from acooler spot to a warmer spot.
If a soup pan is made of glass,we could see the movement of convection currents in thepan. The warmer soup moves up from the heated area at thebottom of the pan to the top where it is cooler. The coolersoup then moves to take the warmer soup's place. Themovement is in a circular pattern within the pan (see pictureabove).The wind we feel outside is often the result of convectioncurrents. You can understand this by the winds you feelnear an ocean. Warm air is lighter than cold air and so itrises. During the daytime, cool air over water moves toreplace the air rising up as the land warms the air over it.During the nighttime, the directions change - the surface ofthe water is sometimes warmer and the land is cooler.41Radiation is the final form of movement of heat energy.
The sun's light and heat cannot reach us byconduction or convection because space is almost completely empty. There is nothing to transfer theenergy from the sun to the earth.The sun's rays travel in straight lines called heat rays. When it moves that way, it is called radiation.When sunlight hits the earth, its radiation is absorbed or reflected. Darker surfaces absorb more of theradiation and lighter surfaces reflect the radiation. So you would be cooler if you wear light or whiteclothes in the summer.2. What Is Electricity?Electricity figures everywhere in our lives.
Electricity lights up our homes, cooks our food, powers ourcomputers, television sets, and other electronic devices. Electricity from batteries keeps our cars runningand makes our flashlights shine in the dark.Here's something you can do to see the importance of electricity.
Take a walk through your school, houseor apartment and write down all the different appliances, devices and machines that use electricity. You'llbe amazed at how many things we use each and every day that depend on electricity.But what is electricity? Where does it come from? How does it work? Before we understand all that, weneed to know a little bit about atoms and their structure.All matter is made up of atoms, and atoms are made up of smaller particles.
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