What is Force?
The push or pull that starts an object moving is a force. Forces not only make things move, they can also speed up or slow down a moving object, make it change direction, or even distort its shape. Generally, the stronger the force, the greater the effect it has on an object.
Pressure
You put pressure on something when you apply a force to it. The amount of pressure depends on two things: the size of the force, and, more importantly, the size of the area on which it is applied. The smaller the area, the greater the pressure. This principle explains why thin stiletto heels sink into wooden floors and damage them. It also explaiifSvhy a camel's large, flat feet prevent it from sinking into the sand in the desert.
Weight
Your weight is the force that you exert on the Earth. It is a result of gravity acting on your body. On the moon, your weight would be much less than it is on the Earth, because of the weaker pull of the moon's gravity. Weight differs from mass: your mass is constant whatever the force of gravity. Scientists measure mass in kilograms (kg). This indicates the amount of matter in your body. Scientists measure weight in newtons (N), and 1 kg equals a force of 9.81 N.
Weights and Measures
Any measurement - for example, of temperature, distance, time, or weight is based on units. A unit is a fixed quantity. In ancient times, body parts were used to measure length. The Greeks used the finger as a basic unit of length, with 16 fingers equaling one foot. Measurement of weight was originally based on how much a man could lift. These imprecise measurements developed into a system of common units.
1. push – толкать, толчок
pull – тянуть, натяжение
speed up – ускорять
slow down – замедлять
pressure –давление
apply –прилагать, прикладывать
size – размер
area - площадь (мат.), область, территория
sink into - проваливаться, утопать measure - измерять, мера unit - единица (измерения) precise - точный common - общепринятый, распространенный, общий, обычный
Notes:
2. stiletto heels - êàáëóêè-øïèëüêè
3. to prevent smb (smth) from doing smth - íå äàâàòü (ìåøàòü) êîìó-ëèáî
(чему-либо) сделать что-либо.
Lesson 10
Metals
Metals are a group of elements that share certain properties. They conduct heat and electricity well, which is why cooking pans and electrical wires are made of metal. They are also strong and can be shaped easily; this is why they are used to make structures such as bridges. Although there are many similarities between metals, there are also differences that determine how suitable a metal is for a particular use. Of the 109 elements known today, 87 are metals. They are rarely used in their pure state - they are usually mixed with other metals or nonmetals to form combinations known as alloys.
Nonmetals
Only 22 of the elements are nonmetals. The properties of nonmetals are usually opposite to those of metals- the other group of elements. For example, they do not usually conduct heat and electricity and they cannot be formed into shapes easily. Useful nonmetals include chlorine, which is used in swimming pools to kill germs, and hydrogen, which is a good fuel. Some elements, although classified as nonmetals, have characteristics somewhere between those of a metal and those of a nonmetal; they are known as semimetals or metalloids.
Alloys
An alloy is an intimate mixture of two or more metals melted together. Mixtures of this kind are generally mechanical in their nature; in some cases, they may form chemical compounds. As a rule, when two metals melted together form an alloy, the substance formed is, for all practical purposes, a new metal.
Metals are usually mixed in their liquid state to form an alloy. If the metals chosen dissolve in each other when they are liquid, the solution will form an alloy after solidification. Metals that do not dissolve in each other when liquid will not form an alloy when they solidify. A steel containing some metallic element other than iron and carbon, is generally known as "special steel". These various metals, when added to steel in certain percentages, increase the hardness and the toughness of the steel.
1) Learn the words:
shape - форма, придавать форму case - случай
determine - определять dissolve - растворяться)
pure - чистый solidify - затвердевать
alloy - сплав hardness - твердость, прочность
Notes:
1)share certain properties - èìåþò íåêîòîðûå îäèíàêîâûå ñâîéñòâà
1) other than iron - íå ÿâëÿþùèéñÿ æåëåçîì (îòëè÷íûé îò æåëåçà)
1) special steel - ëåãèðîâàííàÿ ñòàëü
Lesson 11
1. Learn the words:
cell phone- сотовый телефон surpass - превосходить convenient- удобный X-rays- рентгеновские лучи be aware of - знать assess - оценивать
long - term- длительный, долгосрочный significantly - значительно precaution- предосторожность, меры предосторожности approach - подход
2. Text.
Cell phones
Cell phones are almost as common as pocket change these days. It seems nearly everyone, including an increasing number of children, carries a cell phone wherever they go. Cell phones are now so popular and convenient that they are surpassing landlines as the primary form of telecommunication for many people.
Potential health risks
As cell-phone use continues to grow, so does concern about the possible health risks of prolonged exposure to cell-phone radiation.
Wireless cell phones transmit signals via radio frequency (RF), the same kind of low-frequency radiation used in microwave ovens and AM/FM radios. Scientists have known for years that large doses of high-frequency radiation—the kind used in X-rays—causes cancer, but less is understood about the risks of low-frequency radiation.
Studies on the health risks of cell-phone use have produced mixed results, but scientists and medical experts warn that people should be aware of potential health
risks.
Because cell phones haven't been around very long, scientists haven't been able to assess the effects of long-term cell-phone use, or to study the effects of low- frequency radiation on growing children. Most studies have focused on people who have been using cell phones for three to five years, but some studies have indicated that using a cell phone an hour a day for 10 years or more can significantly increase the risk of developing a rare brain tumor.
How to Protect Yourself from Cell-Phone Radiation
"Precaution" seems to be the approach recommended by an increasing number of scientists, medical experts and public health agencies. General recommendations to minimize the potential health risks include talking on cell phones only when necessary, and using a hands-free device to keep the cell phone away from your head.
Notes:
pocket change -мелкие карманные деньги
exposure to radiation- воздействие радиации (букв, подвергание радиации) cancer- рак
haven't been around very long - используются недавно (появились недавно), tumor- опухоль
Lesson 12
3. Learn the words:
corner - угол (комнаты, улицы)
climb - забираться (на гору, по
лестнице)
numerous - многочисленный powerful - мощный, могущественный
smell - чувствовать запах, пахнуть
communicate - сообщать, передавать информацию
communicator - собеседник sense - чувство destroy - разрушать sea bed - морское дно above all - помимо всего either...or - или...или
4. Text.
The world population
There are five billion people in the world and they live in all different corners of it. They live on the snow and ice of the Poles and in the tropical jungles on the equator. They have climbed the highest mountains and walked on the sea bed. Some of them have even left the earth and visited the moon.
The human species
The human species is the most numerous and the most powerful of all the animals on earth. In many ways, animals can do things better than we can. Dogs can smell and hear better than we can. Cats can see in the dark. Birds can fly thousands of miles away and return to the same place every year. But we are different. No other
animal builds cathedrals, plays football, tells jokes, gets married, has prisons, writes symphonies, elects presidents, or goes to the moon.
