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Chapter 14 Science General Knowledge (2)
Rusting is a chemical change. Rusting is like burning. Rusting joins iron to oxygen. Rusting is a slow chemical change. Burning is a fast chemical change. An orange ripening on a tree is a slow chemical change.
All matter is changing. Some changes happen slowly. Some changes happen fast. It takes a long time for mountains to change. A forest fire can change the trees very fast.
Vocabulary
Grind [ɡraind] vt. & vi. Grind, chew;
vt. to rotate, to press;
n. Grinding, milling, drudgery
molecule ["m?likju:l] n. molecule
dust [d? st] n. Dust, dust, dust, remains;
vt. & vi. brush (a brush), dust (a dust)
tiny ["taini] adj. tiny, tiny
Microscope ["maikr? sk? up] n. Microscope

Substance ["s? bst? ns] n. Matter, subject, subject, substance, ontology

Clay [klei] n. Clay, soil

mold [m? uld] n. mold, mold;
vt. to cast, to shape

Cereal ["si? ri? l] n. Cereal plants, grains, porridge
Digest [dai"d?est] vt. & vi. Digest;

vt. Thorough understanding;

n. abstract, abstract, compilation

baking ["beiki?] n. baking, the amount of baking

spoil [sp? il] vi. to deteriorate;

vt. to damage, ruin, spoil, spoil

Oxygen ["? ksid?? n] n. <chemical> oxygen, oxygen

rusting ["r? sti?] n. rusty
ripen ["raip?n] vt. & vi. mature, make cooked

Practice
I. Write the answer in the blank using the correct word.
1. A change in size or shape is a ．

2. Burning and rusting are examples of a ．

3. When matter gets hot it goes up.

4. All matter is made of a． and b． that are too tiny to see with a microscope.

5. change makes new matter from old matter.

II. Write P for physical change. Write C for chemical change.
1. breaking a window
2. melting ice cream in a cone
3. Digesting your food
4. smashing a piece of clay
5. a forest fire
6. jumping up and down
7. a mud puddle drying out
8. the spoiling of food
Translation
How small can matter be?You can break a stone into many pieces, you can grind a lump of sugar into powder, but what is the smallest thing you can make?Scientists call the smallest substances atoms and molecules.Millions of molecules make up extremely fine dust.Even the most powerful microscopes cannot see atoms and molecules.Everything is made of tiny atoms and molecules.

You can heat things up, you can cool things down, you can break things up, you can change the size and shape of things, all of these changes are physical changes.Physical changes do not change one substance into another.Clay is still clay even if it is cast into shape.Sugar is still sugar, even if you put it in your cereal, sugar doesn't turn into salt.Physical changes simply change the shape and size of matter.

Not all changes are physical changes.Sometimes, when things change, new things are created.This new thing looks and behaves differently from the old thing, and this change is called a chemical change.

Many chemical changes are beneficial.The foods you eat undergo chemical changes, and when you digest foods, your body chemically changes them.When you digest, the food you eat is no longer food.Your body needs to change this food to use it.Digested food gives your body energy.A growing plant exhibits a chemical change in which food and water from the soil and air are converted into plant cells.These chemical changes are beneficial chemical changes, the formation of new things from old things.

When two substances are mixed, a chemical change may occur.Baking a cake is a chemical change where different kinds of substances are mixed together to make a cake baked.Old matter put together in new ways creates new things.

Some other chemical changes may not be as helpful.When food is stored for too long, it will spoil.When food spoils, what happens is a chemical change.Fire is also a chemical change, forest fires are not a beneficial chemical change, but those fires that warm your room are beneficial chemical changes.Combustion, which can be beneficial or not, is a chemical change because it combines some substances with oxygen.

Rust is a chemical change.Rusting, like burning, combines iron and oxygen.Rust is a slow chemical change, burning is a fast chemical change, and oranges ripening on trees are a slow chemical change.

Everything is changing, some very slowly, some very quickly.Mountains change over long periods of time, while forest fires can change trees very quickly.

Exercise
Ⅰ. Fill in the blanks with the correct words.

1.Changes in size and shape change is.

2.Burning and rusting are examples.

3.Things rise when they get heat.

4.All matter is and is made up, and they are so tiny that they cannot be seen with a microscope.

5.Change can change old matter into new matter.

Ⅱ. To judge the following changes, if it is a physical change, write P, and if it is a chemical change, write C.

1.break windows 2.Cone ice cream melts 3.Digest food

4.smash a piece of clay 5．Forest fire 6.jump up and down
7.Muddy puddles dry up 8.Food spoilage

Ⅰ. 1. physical change physical change
2. chemical change chemical change
3. temperature
4. a. atoms atoms b. molecules
5. Chemical

Ⅱ．1．P　2．P　3．C　4．P　5．C　6．P　7．P　8．C
03 Solar System Solar System

The sun, earth, moon, planets, and smaller objects called meteoroids, comets, and asteroids, make up what we call the solar system. He had made the stars, also.
Sun. Our sun is a star. It is the center of our solar system. The earth, moon, planets, and smaller heavenly bodies revolve around the sun. Without the sun, life on this planet earth would be impossible. Without the sun there could be no weather. The tilt of the earth causes our seasons. The heat from the sun moves the air causing the wind. The sun seems to rise in the east and set in the west because of the rotation of the earth. The earth rotates once every twenty-four hours on its axis. The revolution of the earth around the sun occurs once every 365.14 days. Our year is measured by this revolution. The sun also moves. It spins on its axis and rushes through the Milky Way at a speed of 43 miles (000 kilometers) an hour.
Moon. Our nearest neighbor in space, the moon, is about 240 miles (000, 386 kilometers) from the earth. Since the moon has no air or water, no life is there. The gravity on the surface of the moon is only about one-sixth of that on the earth. If a person weighs sixty pounds here on earth, he would weigh only ten pounds on the moon. If he could lift fifty pounds here, he could lift three hundred pounds there. Two astronauts made the first landing on the moon in 160. They brought back samples of soil and rocks for study.
Planets. Do you remember how many planets are revolving around the sun? Nine planets, including the earth, orbit the sun. You will recall that Mercury is the nearest to the sun. The other planets, in order from the sun, are Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto （For twenty years at a time Pluto is closer to the sun than Neptune.）

Stars. The number of stars that we can see on a clear night without a telescope is between three thousand and five thousand. Man has estimated an endless number of galaxies with billions and billions of stars in each galaxy.
Because stars have been studied for centuries by astronomers, some people confuse astronomy and astrology. Astronomy is a scientific study of the universe. Astronomy is a true science. Astrology is superstition. and stars. The Bible warns against believing in astrology. Scientists know that such dependence on the stars is nonsense. We study astronomy to better understand the universe, not to learn about ourselves or our future.
Vocabulary
Meteoroid ["mi: tj? r? id] n. Meteor

comet ["k? mit] n. Comet
asteroid ["?st?r?id] n. (especially those orbiting between Mars and Jupiter) asteroids
rotation [r? u"tei?n] n. Rotate, turn, turn, take turns, take turns

axis ["?ksis] n. axis, axis, centerline, coordinate axis, reference line
spin [spin] vt. & vi. make...rotate;
vt. to make up
Milky Way Milky Way
astronauts ["? str? n?: t] n. Astronauts, astronauts
Orbit ["?: bit] n. Orbit;

vt. & vi. run on... orbit, orbit around

Venus ["vi: n? s] n. Venus, Venus
Mars [mɑ: z] n. Mars
Jupiter ["d? u: pit?] n. 〈day〉Jupiter

Saturn ["s?t?n] n. 〈day〉Saturn

Uranus ["ju:? r? n? s] n. Uranus

Neptune ["neptju:n] n. Neptune

Pluto ["plu: t? u] n. Pluto, the god of the underworld

Telescope ["telisk? up] n. Telescope;
vt. & vi. (to make something) shorten (fold together), embed

confuse [k? n"fju: z] vt. To confuse, to confuse, to confuse, to confuse, to confuse

astronomy [? s"tr?n?mi] n. astronomy

astrology [? s"tr? l? d? i] n. astrology

superstition ["sju:p?" sti? ? n] n. superstition, superstitious behavior

Practice
Write true or false.
1. The earth revolves around the sun causing day and night.

2. The sun travels through the Milky Way at high speed.

3. Without the sun, life on earth would be impossible.

4. Nine planets orbit the sun.

5. Four planets orbit the earth.

6. Astrology is a superstition warned against in the Bible.

7. The earth is the center of the solar system.

8. Comets are smaller objects in space that orbit the sun.

9. Asteroids orbit the moon once every twenty-four hours.

Write the letter of the correct answer on each line.
1. Two astronauts landed on the moon in ．

(End of this chapter)