Unit 1? Tools and machinery
First, use tools.
1.？ A machine is a device that can make us labor-saving or convenient. Screwdriver, hammer, scissors and other mechanical structures are very simple, also known as? Simple machinery? .
2. It is convenient to take the screws out of the wood with a screwdriver and the nails out of the wood with a claw hammer. Different tools have different uses.
Second, the science of leverage
1. A simple machine like a crowbar is called. Lever? .
2. There are three important positions on the lever: the position that supports the lever and enables it to rotate around the axis is called the fulcrum; The position of the force on the lever is called the force point; The position where the lever overcomes the resistance is called the resistance point.
3. When the distance from the resistance point to the fulcrum is less than the distance from the force point to the fulcrum, the lever saves effort; When the distance from the resistance point to the fulcrum is greater than the distance from the force point to the fulcrum, the lever is laborious; When the distance from the resistance point to the fulcrum is equal to the distance from the force point to the fulcrum, the lever is neither labor-saving nor laborious.
There is a fulcrum on the lever ruler, and the distance from the fulcrum is marked on the left and right sides, which is a good tool for studying lever.
Third, the research of lever tools.
1. Among the commonly used lever tools, labor-saving levers include: hammer, claw hammer, vise, bottle opener, wire stripper, garden scissors, steelyard, pressure lever of hydraulic well, etc. The laborious levers are: poker, tweezers, chopsticks, barber scissors, etc. The labor-saving levers are: seesaw, balance, etc.
2. Some lever tools are designed with great effort, because they have convenient benefits (such as tweezers, pliers, fishing rods, etc.). ).
3. "Although the weight is very small, it can weigh a thousand kilograms". Is that the steelyard used? The result of lever principle (rope is fulcrum, weight is stress point and weight is resistance point).
The forearm bone on our body is like a lever, the elbow joint is the fulcrum, the place where we hold the object is the resistance point, and the biceps brachii of the upper arm is the stress point.
Archimedes once said, "As long as I have a fulcrum in the universe, I can pry up the earth with a long stick." The stick here is equivalent to a lever.
Fourth, the secret of the axle
1. Like a faucet, a machine with wheels and shafts fixed together is called. Axle? . A screwdriver is a shaft tool. What is its handle? Wheels, what is an arbor? Axis? .
2. Is it time-saving to drive the axle on wheels? Force; When the wheel is driven by the force on the shaft. Cost? Force.
3. Axles can save labor. The bigger the wheel, the more energy will be saved when the wheel is used to drive the shaft to rotate. So the handle of a screwdriver is always more important than the handle? Rough? Some.
4. The wrench is sleeved on the nut to form a shaft? At this time, the whole wrench is a wheel? The nut part is a shaft.
5. Axles in life: faucets, door handles, car steering wheels, wrenches, pulleys, etc.
Five, crown block and moving pulley.
1. Like the pulley at the top of the flagpole, the pulley that can't rotate in one position is called the crown block; Can the crown block change the direction of force? , but can't? Save effort.
2. What is the name of the pulley on the hook of tower crane that can move with the weight? Moving pulley; Moving pulleys can save effort? , but can't? Change the direction of force? . ? This force is measured with a dynamometer. Newton is the unit of force, represented by the letter "n".
Six, pulley block
1. The pulley block is composed of a crown block and a moving pulley. Using pulley block can not only save labor, but also change the direction of force.
2. The crown block and moving pulley are combined into the simplest pulley block. The more pulley blocks, the more pulley blocks. Save effort? .
3. The crane uses a pulley block.
4.① Name: crown block ② Name: moving pulley ③ Name: pulley block ④ Name: multiple pulley blocks.
Role played:? Role played:? Role played:? Role played:
? Change the direction of force? Can save both labor and effort? Not only can labor be saved
Can't save effort, can't change the direction of force and can change the direction of force? And you can change the direction of the force.
If you use them to lift 50 kilograms of the same weight, the most labor-saving is (④), followed by (②, ③), and the least labor-saving is (①).
Seven, the role of slope
1. A simple machine like a board on a car compartment is called. Oblique angle .
2. The inclined plane can save energy, and the slope of the inclined plane is larger. The smaller the strength, the greater the slope and the smaller the strength.
3. There are many places where inclined planes are used in life, such as "S" type Panshan Highway, various slopes, various blades, threads, approach bridges of viaducts and so on.
4. The thread of the screw is the deformation of the inclined plane. Screws with the same thickness, the denser the thread, the easier it is to screw into the wood.
Step 5 ask questions:
Question to be studied: Does the inclination of the inclined plane affect labor saving?
My hypothesis: the inclination of the inclined plane has an influence on the amount of labor saving, and the smaller the inclination, the more labor saving.
Conditions to be changed: What is the gradient of the slope (the height of the block)?
Conditions that will not change:? The same weight, the same board, improves the speed of loading;
Experimental method: (1) Put a board on wood blocks with different heights to make several inclined planes with different slopes; (2) Hook a heavy object with a dynamometer, and lift the heavy object along inclined planes with different slopes at the same speed; (3) Record and compare the forces exerted on each inclined plane.
Eight, simple machinery on the bicycle
1. Is the bike used? Levers (such as buttons for brakes and bells), axles (such as handles and pedals), Bevel (such as screw)? Simple mechanical principle. These simple machines play a labor-saving or convenient role.
2. The relationship between the rotation speed of the gear on the bicycle and the gear size is: When the big gear drives the small gear to rotate, does the small gear rotate much more than the big gear? Fast; When the pinion drives the big gear to rotate, does the big gear rotate much more than the pinion? Slow? .
Synthesis: Please relate the following items to the simple mechanical principles applied.
Oblique angle Axle? Lever pulley
Screwdrivers, tweezers, screws, taps, cranes, axes, wire strippers? Brakes
Unit 2? Shape and structure
First, resist bending.
1. There are vertical "columns" and horizontal "beams" in buildings and bridges, and beams are easier to bend and break than columns. In order to improve the bending capacity of the beam, we usually put the beam up.
2. To improve the bending resistance of materials, we can increase the width, thickness and shape of materials.
3. With the increase of paper width, the bending strength will also increase; With the increase of paper thickness, the bending strength will increase greatly.
Step 4 ask questions:
Question to be studied: Is the thickness of paper related to the bending strength?
Experimental materials: two stacks of books, four A4 sheets of paper, double-sided tape and several washers?
The experimental hypothesis is that the thickness of paper is related to the bending capacity, and the thicker the paper, the stronger the bending capacity. ?
Experimental steps: ① Take two stacks of books as piers, put a piece of paper on them, and measure how many washers can bear at most; (2) Put two pieces of paper (at both ends) and measure how many washers can bear at most; (3) Put four pieces of paper (stick them together) and measure how many washers they can bear at most; ④ Compare the results and draw a conclusion.
The quantity to be changed in the experiment: the thickness of the paper beam; The constant quantities are: the height and width of the pier, the size of each piece of paper, the weight of each washer, and the degree to which the paper is crushed.
In this experiment, we use the number of load-bearing washers to represent the bending capacity of paper beams.
Second, the shape and bending resistance
1. Bending sheet material into the shape of "V", "L", "U", "T" or "I" can greatly enhance the bending capacity of the material, although the width of the material is reduced.
2. Generally, the beam is placed vertically, because the beam is placed vertically, which reduces the width of the material, but increases the thickness and greatly enhances the bending capacity of the beam.
3. Why can the structure of corrugated board make soft paper hard? Because the middle structure of corrugated paper is W-shaped, although the width of the material is reduced, the bending resistance of the material is greatly enhanced by increasing the thickness.
Third, the power of the arch.
1. When the arch bears the weight, the pressure can be transmitted downward and outward to the adjacent parts, and the various parts of the arch are squeezed and combined more closely. When the arch is compressed, it will produce an outward force, and when it resists this force, the arch can bear a lot of weight.
2. The arch foot can keep the shape of the arch unchanged, and the arch can bear more weight.
Fourth, find an arch.
1. The dome shape can be regarded as a combination of arches, which has the characteristics of bearing large pressure and not producing outward force.
A sphere can be regarded as an arch in all directions, which makes it stronger than any other shape. (For example, when an egg is pinched by hand, it won't be fragile.)
3. The top and bottom of the plastic bottle are approximately dome-shaped, and the middle is cylindrical. The thickest and hardest is in the bottle mouth, and the thinnest and softest is in the bottle body.
The structure of the human body is very delicate. The skull is almost spherical and can protect the brain well; Arched ribs guard the internal organs in the chest; People's foot bones form an arch, which can better bear the weight of the human body.
5. Arch in life: rib, arch, arch, arch window, arch bridge; Dome shape: turtle shell, shell and helmet; Sphere: eggshell, fruit, skull, table tennis.
6. With the same amount of material, the hollow tube is much thicker than the solid rod, and the bending capacity in any direction is the same, that is, it is light in weight and high in strength. This principle applies to the tubular arm bones, leg bones, stems and steel pipes of plants.
Fifth, make a framework.
1. A skeleton structure like an iron tower is called a frame structure. Triangular frames have the characteristics of stability.
2. Rectangular frames, cubical frames and diagonal bars are equivalent to triangles inside, which can play a reinforcing role.
Sixth, build a tall tower.
1. A tall building can be built with very little material, and the basic structure of the frame structure is a triangle.
2. Structural characteristics of the frame tower: ① Small on the top and large on the bottom? 2 light up and heavy down? ③ Small wind resistance? ④ A large number of triangular frame structures are adopted.
VII. Shape and Structure of Bridges
1. For an arch bridge with a bridge deck under the arch, the bridge deck can pull the arch foot to offset the outward thrust of the arch, thus reducing the burden on the pier. The bridge deck is also relatively low and flat, which is convenient for traffic.
2. The steel cable can bear great tension, and the steel cable bridge built with it greatly increases the spanning capacity of the bridge.
3. Structure of cable bridge: It consists of steel cables, bridge towers and bridge decks. The cable is the main load-bearing component of the bridge, and the pylon is the main component supporting the cable. The bridge tower was built high to reduce the tension of the steel cable.
Eight, build a bridge with paper.
1. What problems should be considered when designing bridges with paper: ① the characteristics of paper; (2) What are the characteristics of paper durability? ③ Choose the shape and structure; ④ What methods are used to enhance the bending resistance of paper?
2. The total length of Hangzhou Bay Bridge is 36 kilometers, ranking first among the bridges under construction and built in the world. It was officially opened to traffic on May 1 2008.
3. Indicators for evaluating bridge quality: ① Whether it is firm; (2) whether to save materials; 3 whether it is beautiful.
Unit 3? vitality
First of all, electricity and magnetism
1. When current passes through a wire, magnetism will be generated around the wire.
2. 1820, Danish scientist Oster found in an experiment that the compass will deflect when the electrified wire is close to it.
3. If the circuit is short-circuited, the current will be strong and the battery will run out soon, so disconnect it as soon as possible.
4. When doing the experiment of electrified coil and compass, the coil is placed vertically, the compass is placed flat in the center of the coil, and the deflection angle of the compass is the largest.
Second, the electromagnet
1. A device composed of a coil and an iron core like this is called an electromagnet.
2. Electromagnets have a north pole and a south pole. The connection between the south and north poles of electromagnet and the positive and negative poles of battery is related to the winding direction of coil. When the connection mode of the positive and negative poles of the battery changes, its magnetic poles will also change. When the winding direction of electromagnet coil changes, its magnetic pole will also change.
3. Similarities between electromagnets and magnets: both are magnetic; Both have north and south poles.
The difference between electromagnet and magnet: (1) Magnet is ferromagnetic iron, and electromagnet consists of coil and iron core;
(2) The electromagnet is magnetic only when it is energized, and the magnet does not need to be energized;
(3) The north and south poles of the magnet will not change, but the north and south poles of the electromagnet can change;
(4) The magnetic force of electromagnet can be changed, and the magnetic force of magnet is relatively stable.
Iii. Magnetic force of electromagnet (1)
1. The magnetic force of electromagnet can be changed, which is related to the number of batteries, the number of coils and the size of iron core.
2. Experimental research plan on the relationship between electromagnet magnetic force and coil number.
The problem of research
Is there a relationship between the magnetic force of electromagnet and the number of coils?
Our hypothesis
Related, the number of coils is large and the magnetic force is large; The number of coils is small and the magnetic force is small.
Factors to be tested (changing conditions)
Coil turns
How to change this situation?
1.20 turn coil
2.40 turn coil
3.60 turn coil
The experiment should keep these conditions unchanged.
The number of batteries, the thickness of wires, the size of iron core, the winding direction of coils, etc.
Experimental conclusion
The magnetic force of electromagnet is related to the number of coil turns: the more coil turns, the greater the magnetic force; The number of coils is small and the magnetic force is small.
Fourth, the magnetic force of electromagnet (2)
1. Research plan for testing the relationship between electromagnet magnetic force and battery quantity
The problem of research
Is the magnetic force of electromagnet related to the number of batteries?
Our hypothesis
Related, the number of batteries is large and the magnetic force is large; The number of batteries is small and the magnetic force is small.
Factors to be tested (changing conditions)
Number of batteries
How to change this situation?
1. Battery 1
2.2 batteries
3. Three batteries
The experiment should keep these conditions unchanged.
The number of turns of the coil, the thickness of the wire, the size of the iron core, the winding direction of the coil, etc.
Experimental conclusion
The magnetic force of electromagnet is related to the number of batteries: the number of batteries is large and the magnetic force is large; The number of batteries is small and the magnetic force is small.
2. In scientific inquiry, the order of inquiry is: ① Ask questions; (2) establish a hypothesis; ③ Design the experimental scheme;
④ Collect facts and evidence; ⑤ Test hypothesis; 6 communication.
Five, the magic small motor
1. The function of the commutator is to switch on the current and change the direction of the current. When the small motor rotates, the brush contacts the three metal rings of the commutator in turn, and the direction of current passing through the rotor coil will automatically change.
2. Small motor includes shell, rotor and back cover. There are a pair of permanent magnets in the shell, an iron core, a coil and a commutator on the rotor, and a brush on the back cover.
3. A motor is a machine that uses electricity to generate electricity. Although the size is very different and the structure is different, the basic principle of motor work is the same: electricity produces magnetism, and the interaction of magnetism rotates.
VI. Electricity and Energy
1. Energy has different forms, such as electric energy, thermal energy, light energy and sound energy. Moving objects also have energy, called kinetic energy. Energy is also stored in fuel, food and chemicals, which is called chemical energy.
Everything needs energy to work. Without energy, there would be no movement and change in nature, and there would be no life.
Input energy form
household appliances
Energy form of output
Electricity? can
Rice cooker
heat energy
electric fan
kinetic energy
television
Light energy and sound energy
Electricity? light
optical energy
Electricity? kiln
heat energy
All electrical appliances are electric energy converters, which can convert the input electric energy into other forms of energy.
Where does the electricity come from?
1. Various batteries: dry batteries (ordinary batteries and button cell)-chemical energy is converted into electrical energy; Solar cell-solar energy is converted into electric energy; Battery-converts chemical energy into electrical energy when discharging, and converts electrical energy into chemical energy when charging.
When an electric motor is used to generate electricity, it should be called a generator.
3. Source and conversion of electric energy
Electric energy source
Converted energy
Energy form of output
Ordinary battery
chemical energy
electric energy
photocell
optical energy
hydropower station
kinetic energy
Heating and power plants
heat energy
nuclear power plant
nuclear power
Eight, energy and the sun
1. Coal is transformed from ancient plants. After plants died hundreds of millions of years ago, they were covered with sediments and isolated from the air. After the crustal changes, they were buried deep underground and slowly turned into coal under the action of high temperature and high pressure for a long time.
2. Oil and natural gas were formed by long-term complex changes of a large number of lower organisms hundreds of millions of years ago.
The energy possessed by coal, oil and natural gas is solar energy stored for hundreds of millions of years.
4. New energy: geothermal energy, wind energy, tidal energy, nuclear energy, solar energy, ocean energy, etc.
5. Coal, oil and natural gas are non-renewable energy sources. Use a little and use less. We are running out of energy, so we should save energy.
Unit 4? biological variability
First, campus biological search
1. More than 2 million species have been discovered and classified so far, and it is estimated that there should be 2-4.5 million species on the earth.
Scientists often investigate the species and distribution of animals and plants in an area. Sub-regional observation and research is a common method in scientific research.
3. Attention should be paid to the investigation of plants and animals on campus: ① Don't pick plants and harm animals; Hidden animals can be inferred from footprints, feces, hair and other traces, and birds that often fly should also be recorded; (3) Looking for small animals living underground, take a spatula, preferably a magnifying glass; ④ Unknown animals and plants can be recorded by painting, photographing and other appropriate methods; ⑤ Record while investigating, and try not to miss every kind of animals and plants on campus.
Second, the campus biological distribution map
1. There are many kinds of plants and animals on campus, and the living environment is also different.
2. The rare plants in China are Davidia involucrata, Ginseng, Metasequoia glyptostroboides, Ginkgo biloba, camellia, etc.
Rare animals in China include giant panda, Tibetan antelope, Chinese alligator, baiji, Asian elephant and golden monkey.
Third, all kinds of plants.
1. Classification can help us to better distinguish and study animals and plants.
According to different standards, plants can be divided into different kinds. For example, according to the characteristics of stems, plants can be divided into woody plants (such as peach trees and camphor trees) and herbs (such as green bristlegrass and rice); According to the living environment, plants can be divided into aquatic plants (such as duckweed and peanut) and terrestrial plants (such as cedar).
Scientists classify plants mainly according to their characteristics. For example, they divide plants into two categories according to whether they have flowers or not: flowering plants and non-flowering plants.
4. In the plant kingdom, more than 300,000 species have been found, of which flowering plants account for more than half.
Among non-flowering plants, ferns, algae and mosses, like flowering plants, make their own food through photosynthesis.
6. Non-flowering plants include ferns (such as bracken), algae (such as laver) and bryophytes (such as cucurbitaceae).
7. Flowering plants are: peach trees, rape, impatiens, roses, Ceratophyllum, etc.
Fourth, there are many kinds of animals.
1. Scientists divide animals into vertebrates and invertebrates according to the characteristics of bones. Animals with spines are called vertebrates, and animals without spines are called invertebrates.
2. Like ants, locusts and bees, animals with three feet are insects; Like goldfish and carp, they live in water all their lives, and the animal that breathes through gills is fish; Animals with feathers are birds; Mammals give birth to small animals directly and feed them with milk. Reptiles: The skin is covered with scales or armor, and the abdomen crawls close to the ground. Amphibians: When they were young, they lived in water and breathed through their gills. When they grow up, they live on land and breathe with their lungs.
3. The body structure and life activity characteristics of animals are important criteria for scientists to classify animals.
4. In the animal kingdom, more than10.5 million species have been found, which is the highest in the life world. Insects are the largest species in the animal kingdom, with more than 6,543,800 species known, accounting for about 80%.
5. Vertebrates are a kind of animals with complex structures, which can be divided into fish, amphibians, reptiles, birds and mammals.
Vertebrate: Mammals: bats, sheep, rabbits, pigs, whales and seals.
Bird? Category: chicken, duck, goose, eagle, goose, owl.
? Reptiles: geckos, snakes, crocodiles, turtles, lizards and turtles.
? Amphibians: toad, salamander, giant salamander.
? Fish? Class: hippocampus, crucian carp, eel, loach, eel, carp, goldfish.
Fifth, we look different.
1. Different creatures have different characteristics.
We can't find two people who look exactly alike.
3. There are two kinds of people with different looks in a role; There are four kinds of people with different looks when the two qualities are combined; The 40-character combination has 1 trillion people with different looks.
Six, the original text is interrelated.
1. The leaves of plants have photosynthesis and transpiration. Cactus lives in a desert that lacks water. In order to reduce the evaporation of water, the leaves degenerate into spines, and the stems are green, plump and juicy, which bear the functions of photosynthesis and water storage. Pine trees have a wide range of life, and needles can reduce water evaporation and help maintain body temperature; Bananas live in tropical areas rich in water, and their leaves are wide, which is more conducive to evaporating water in the body and regulating the temperature of plants. The different morphological structures of plants are the result of their long-term adaptation to the living environment.
2. Animals living in different environments also have obviously different morphological structures.
3. Duckweed is a floating plant among aquatic plants, with a degenerated root system and only one fine root; Grass and corn live on land. Roots not only fix plants in the soil, but also absorb water from the soil for plants to survive, so they all have huge roots.
4. The morphological structure of organisms is related to their living environment and habits. Cats have meat pads on their feet, which make a small noise when running on the ground and are not easy to be found by predators; Hook-shaped bird claws are easy to grasp the trunk, which is suitable for living in the forest and is conducive to catching small animals; Ducks have webbed feet, which can be used for paddling and are suitable for living in water. Xanthium sibiricum seeds have thorns, which are easy to be carried and spread by animals when living on land; Lotus seeds have a hard shell and can drift in the water; Dandelion seeds are hairy and easy to drift with the wind.
Animal name
living environment
physical features
function
goldfish
water
gill
Breathe in the water
fin
Swim in the water
Spindle (spindle)
Reduce the resistance of water to it
Have scales on your body
Protect the body
pigeon
air
feather
Thermal insulation, waterproof, flight
Hollow bone
The fuselage is light and easy to fly.
With wings
Air flight
Beaked
food
Seven, who chose them?
1. In the wild, green frogs are preserved because of their good camouflage, and frogs of other colors are eaten by predators because they are too conspicuous.
2. Biologists found a very interesting phenomenon when comparing biological individuals in different places, that is, the colder the same creature, the bigger the individual, and the closer the body is to a circle; And the exposed nose, ears, legs and other organs are relatively small.
3. With the change of environment, the morphological structure of animals also changes. All kinds of creatures are caused by all kinds of environments.
4. Natural selection has changed the living things, but artificial selection is also enriching the species diversity.
In the experiment, we found that the water temperature in a large spherical flask dropped slowly, while that in a slender glass bottle dropped rapidly. In nature, animals with big and round bodies cool down slowly.
Eight. The importance of biodiversity
1. The earth is our beautiful home. All kinds of creatures play different roles in this family. They depend on each other, interact and influence each other.
2. Biodiversity is the foundation of human survival and development.
Every living thing is closely related to human life. Human beings cannot live without biodiversity.
All kinds of creatures have different values to us. Some have appreciation value and scientific value, some have economic value and some have medicinal value.
Just as human life is inseparable from biodiversity, every living thing needs to live in an environment with biodiversity. For example, flowers need insects to help pollinate their offspring; Xanthium sibiricum spreads seeds through animals; Animal excreta can be used as food for plants; Grasshoppers need to feed on plants such as rice.
6. To protect biodiversity, we should start with protecting biodiversity in our hometown.
7. Human beings are members of the biological family, so we should treat every member of the family equally.
8. Plants are indispensable to human life: they provide food for human beings; For people to appreciate; As a medicinal material, it is provided to humans; Humans can use plants to make daily necessities and school supplies; Can purify the air; Provide food for animals.
Database:
1. The basic living conditions of living things include sunshine, air, water and region.
2. Biodiversity refers to all living things in the biosphere on earth, as well as their genes and living environment. It includes three levels: species diversity, genetic diversity and ecosystem diversity.
The existence of living things is a natural right, not a human right.
4. The Treaty on Biological Diversity was formally implemented in 1993.
May 22nd every year is called International Biodiversity Day.
6. More than 65,438+080 countries in the world have become parties to the Convention on Biological Diversity.
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