Sixth grade volume I Chinese textbook (2008) people's education press lesson 1 What's the requirement Send it to me

Sixth grade volume I Chinese textbook (2008) people's education press lesson 1 What's the requirement Send it to me

Visiting friends in the mountains
Li Hanrong, a famous poet and essayist, describes a vivid picture of rain in a mountain village. The author mainly visits "friends" old bridge, birds, dewdrops, trees, mountain springs, streams, waterfalls, cliffs, white clouds, skylarks, fallen flowers, fallen leaves and so on
Topic "visiting friends in the mountains"
From the lines of the article, we can really feel that in the eyes of the author, every flower, tree, bird, stone, grass and tree in the forest has become a living person. They can talk to us, can communicate with us, and they have become our friends. So when the author goes into the mountains to see the scenery, he naturally becomes a "visiting friend in the mountains."
The roots grow under my feet, deep into the soil and rock; the hair grows into a crown, the arms become branches, and the sap of the tree beside the blood revolves and flows in the rings
This is the association of the author walking into the woods and leaning on a tree. The tree is a friend, a friend of the tree, and the tree and people are integrated into one. What a wonderful state it is! From these associations, we can really feel the "confidant" friendship between the author and the tree, the state of entering the nature of things and me
Text Organization
The first paragraph (NATURAL paragraphs 1 and 2): I'm going to visit my old friends in the mountains. The second paragraph (NATURAL paragraphs 3 and 7): I've visited some friends in nature, such as ancient bridges, woods and mountain springs. The third paragraph (natural paragraph 8): I say goodbye to my friends in the mountains
The full text expresses the author's love for nature
We've all memorized it. I don't know if it's the same as you

What's the composition in unit 1 of the sixth grade Chinese textbook of PEP

1、 Self account of XX (animal and plant)
2、 Wonderful sound world
3、 Summer life

A particle starts to move in a straight line with uniform acceleration from rest, and the acceleration is A1. After time t, it moves in a straight line with uniform deceleration, and the acceleration is A2. If it can return to the starting point after time t, then A1: A2 should be ()
A. 1：1B. 1：2C. 1：3D. 1：4

There are: X1 = 12a1t2 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; in the acceleration stage, the displacement is: x2 = v0t − 12a2t2 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; in which: V0 = a1t & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X1 = - x2 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; in the deceleration stage; ③ Simultaneous solution: A1: A2 = 1:3, so abd is wrong, C is correct, so select C

All the formulas of junior high school physics
The more detailed the better

Unit formula of physical quantity
Name symbol name symbol
Mass m kg m = PV
Temperature T ° C ° C
Velocity v m / S M / S v = s / T
Density p kg / M & sup3; kg / M & sup3; P = m / V
Force (gravity) f Newton (cow) n g = mg
Pressure P Pascal PA P = f / S
Work w Joule (joule) J W = FS
Power P watt W P = w / T
Current I a (a) a i = u / R
Voltage U V U = IR
Resistance R ohm (Ω) r = u / I
Electric work w Joule (joule) J W = uit
Electric power P watt (watt) W P = w / T = UI
Heat Q Joule J Q = cm (T-T °)
Specific heat C coke / (kg ° C) J / (kg ° C)
The speed of light in vacuum is 3 × 108 M / s
G 9.8 N / kg
Sound speed 340m / s in air at 15 ° C
The safety voltage is not higher than 36 v
Outline of basic concepts of physics in junior middle school
1、 Measurement
1. Length L: main unit: meter; measuring tool: scale; when measuring, it should be estimated to the next digit of the minimum scale; the unit of light year is length unit
2. Time t: main unit: second; measuring tool: clock; stopwatch in laboratory. 1 hour = 3600 seconds, 1 second = 1000 milliseconds
3. Mass m: the amount of material contained in the object is called mass. Main unit: kilogram; measuring tool: scale; pallet balance for laboratory
2、 Mechanical movement
1. Mechanical movement: movement in which the position of an object changes
Reference: to judge the motion of an object, another object must be selected as the standard
2. Uniform linear motion:
① There are two ways to compare the speed of movement: A to compare the distance passed in the same time. B to compare the time required to pass the same distance
② Formula: 1 m / S = 3.6 km / h
3、 Strength
1. Force F: force is the action of objects on objects. The action of forces between objects is always mutual
Unit of force: Newton (n). Instrument for measuring force: dynamometer. Spring scale is used in laboratory
The effect of force: to deform or change the state of motion of an object
The change of object motion state refers to the change of object velocity or motion direction
The three elements of force: the size, direction and action point of force are called the three elements of force
The diagram of force should be scaled; the diagram of force should not be scaled
Gravity g: the force exerted on an object due to the attraction of the earth
Relationship between gravity and mass: g = mg m = g / g
G = 9.8 N / kg. Pronunciation: 9.8 N / kg, which means that the weight of an object is 1 kg and the gravity is 9.8 n
Center of gravity: the point of action of gravity is called the center of gravity of an object. The center of gravity of a regular object is at the geometric center of the object
4. Balance condition of two forces: acting on the same object; equal magnitude and opposite direction of two forces; acting on a straight line
Under the balance of the two forces, a body can be stationary or move in a straight line at a constant speed
The equilibrium state of a body means that the body is in a state of static or uniform linear motion. The resultant force of the external force on the body in equilibrium state is zero
5. The combination of two forces on the same line: the direction is the same: the resultant force F = F1 + F2; the resultant force direction is the same as that of F1 and F2;
The direction is opposite: the resultant force F = f 1 - F 2, the direction of resultant force is the same as that of large force
Under the same conditions, the rolling friction is much smaller than the sliding friction
Sliding friction is related to normal pressure, material properties and roughness of contact surface
7. Newton's first law is also known as the law of inertia. Its content is: all objects always keep static or uniform linear motion state when they are not affected by external force. Inertia: objects have the property of keeping original static or uniform linear motion state, which is called inertia
4、 Density
1. Density ρ: the mass per unit volume of a substance. Density is a property of a substance
Formula: M = ρ V, international unit: kggm3, common unit: g / cm3,
The relationship is: 1g / cm3 = 1 × 103kg / m3; ρ water = 1 × 103kg / m3; ρ water = 1 × 103kg / m3;
Reading: 103 kg per cubic meter, which means the mass of 1 cubic meter of water is 103 kg
2. Density measurement: mass measurement with pallet balance and volume measurement of solid or liquid with measuring cylinder
Area unit conversion:
1cm2 = 1 × 10-4m 2,
1 mm2 = 1 × 10-6 m2
5、 Pressure
Pressure P: the pressure on the unit area of an object is called pressure
Pressure F: force acting vertically on the surface of an object, unit: n
The effect of pressure is expressed by pressure, which is related to pressure and area
Pressure unit: n / m2; special name: Pascal (PA)
Formula: F = PS [S: area under force, common part of two objects in contact; unit: M2]
Methods to change the pressure: ① reduce the pressure or increase the stress area, can reduce the pressure; ② increase the pressure or reduce the stress area, can increase the pressure
2. Internal pressure of liquid: [measurement of internal pressure of liquid: use liquid manometer (U-tube manometer)]
Causes: due to the gravity of the liquid, pressure is produced on the bottom of the container; due to the fluidity of the liquid, pressure is produced on the wall of the container
Rules: ① at the same depth, the pressure in all directions is equal; ② the greater the depth, the greater the pressure; ③ different liquids at the same depth, the greater the liquid density, the greater the pressure
The formula: P = ρ GH H: unit: m; ρ: kg / m3; g = 9.8 N / kg
3. Atmospheric pressure: the atmospheric pressure is produced by the action of gravity. It is the madeburg hemispheric experiment that proves that atmospheric pressure exists and is very large. It is Torricelli (Italian scientist) who determines the value of atmospheric pressure. After the Torricelli tube is tilted, the height of the mercury column remains unchanged and the length becomes longer
1 standard atmospheric pressure = 76cm mercury column height = 1.01 × 105Pa = 10.336m water column height
Instruments for measuring atmospheric pressure: Barometer (mercury barometer, box barometer)
Atmospheric pressure changes with altitude: the higher the altitude, the lower the atmospheric pressure, that is, the higher the altitude, the lower the boiling point
6、 Buoyancy
1. Buoyancy and its cause: an object immersed in liquid (or gas) is supported upward by liquid (or gas), which is called buoyancy. Direction: vertical upward; cause: pressure difference between liquid and object
2. Archimedes principle: objects immersed in liquid are subject to upward buoyancy, and the buoyancy is equal to the gravity of objects expelling liquid
That is, f floating = g liquid discharge = ρ liquid GV discharge
3. Buoyancy calculation formula: F floating = G-T = ρ liquid GV discharge = f upper and lower pressure difference
4. When the object floats: F floats = g and ρ g and ρ 2F

As shown in the figure, the smooth metal ring with radius of R and mass of M is put on the ring. At the same time, one end of a string with length of R is tied to the ball. The ball must be subjected to gravity and the elastic force of the ring. The rope has tension only when it is tensioned. Therefore, in the critical case, the rope is just straightened, but there is no tension. At this time, according to the geometric relationship, the elastic force is inclined upward to 30 ° with the horizontal, The radius of rotation is rcos30 ° so a = gcot30 ° and a = w ^ 2 * rcos30 ° get the critical value w = root (2G / R). For all values greater than W, tension will be generated in the rope, and for all values less than W, the rope will relax. At this time, from the geometric relationship, it can be seen that the elastic force is inclined upward to 30 ° with the horizontal. Why?

The ball must be subjected to gravity and the elastic force of the ring. The rope has tension only when it is tensioned
Therefore, in the critical case, the rope is just straight without tension. At this time, from the geometric relationship, it can be seen that the elastic force is inclined upward to 30 ° with the horizontal, and the rotation radius is RCOs 30 °
So a = gcot30 °
And a = w ^ 2 * RCOs 30 degree
The critical value w = root sign (2G / R)
For all values greater than W, there will be tension in the rope, and for all values less than W, the rope will relax

How much is 360 microampere

1A (a) = 1000mA (MA) = 1000000 μ a (MA)
360 μ a 0.00036 a

On Newton's second law
15. The wire rope of the crane is used to lift 4T goods with an acceleration of 2m / S2. The air resistance of the goods in the process of rising is 200N. The pulling force of the wire rope on the goods is calculated
I think the problem on the first floor is wrong. I calculated 32200 and the answer is the same number. But the analysis on the first floor is reasonable. Which is the positive solution?

Wrong thinking on the first floor. The velocity direction of the object has nothing to do with the acceleration direction
Through the force analysis of the goods, the vector sum of gravity, resistance and pulling force is obtained
The positive direction can be set as downward. Because the gravity and resistance directions are downward, the sign is positive
The pull is up, so the sign is negative
According to Newton's second law
ma=G+f-F
4000*2=40000+200-F
F=32200
G is gravity, f is resistance and F is tension

The two sides of a triangle are equal, the perimeter is 18cm, one side of the triangle is 5cm, and the other two sides are calculated

5cm, 8cm or 6.5cm, 6.5cm

The wooden box with mass m is placed on the horizontal ground, the upper end of a light spring is fixed on the top plate of the wooden box, and the lower end is tied with a small ball with mass M. now the small ball vibrates up and down, and the wooden box never leaves during the vibration process