What is the matter of motion and rest in the second year of junior high physics?

Both motion and rest are relative to the referent.

Motion is the form of existence and intrinsic property of matter. It includes all the changes and processes in the universe. Dialectical materialism holds that the world is material, and matter is in eternal motion.

Matter and motion are inseparable, and there is no matter in the world that does not move, and there is no movement that leaves matter.

Dialectical materialism holds that motion is an intrinsic property and mode of existence of matter, which is absolute and unconditional, but does not deny stillness. It points out that rest is a special case of motion when it is examined in a certain relationship, which is relative and conditional.

Although everything is in motion all the time, a specific thing may not have a certain form of motion on a certain occasion. To the extent that it does not have this particular form of motion, it is stationary. For example, a building on the ground is stationary in the sense that it is not mechanically moving to the ground.

But this stillness is only from a certain"Frame of reference"It seems that this is the case, from something else"Frame of reference"It seems to be in motion, such as buildings orbiting the sun with the ground, moving in the Milky Way with the solar system, and so on.

Everything is in motion all the time, but not all of them change qualitatively. When a thing has not yet undergone a qualitative change, the thing is still itself, and in this sense it is static. For example, when the number of protons in the nucleus does not change, it is still the atom of a certain chemical element and not the atom of another chemical element; While the economic base and superstructure of capitalist society still exists, it remains capitalist and not otherwise.

But in the absence of a change in the chemical properties of atoms, in the absence of a change in the nature of capitalist society, their internal movements are still in motion, and in the final analysis, they are going to cause a qualitative change in them. Therefore, stillness is conditional, temporary, relative, and only a manifestation of motion, while motion itself is unconditional, eternal, and absolute.

It is not a purely negative and conservative factor, but a necessary condition for the existence and development of things.

It is precisely because things have a relatively static aspect that they can become things with definite properties and definite forms of motion and stillness, and can exist and develop, and be recognized and used by people. Modern science has shown that even microscopic particles with extremely short lifespans have a relatively stationary side at the moment of their existence, and have definite properties that can be observed and described.

It is precisely because things have a relatively static aspect that the motion of things becomes something that can be measured and calculated. For example, to calculate the displacement of an object, it is necessary to select a certain frame of reference as the framework at rest; This choice is possible because relative stillness exists objectively.

It is precisely because things have a relatively static aspect that it is possible to grow new factors within things, and to prepare the conditions for the development of things into a higher form. For example, all social forms have a relatively stable or relatively static aspect, so that the productive forces can develop internally, and finally promote the transformation of a social form into a higher social form.

Judging whether an object is at rest or in motion is relative to the reference object, and it is necessary to explain the state of motion of another object according to the state of the reference object, whether it is stationary or in motion.

Motion and rest are divided into two concepts, one is absolute and the other is relative. Middle school physics is about the concept of relativity. For example, bus stop signs and buses, the bus stops at the stop sign and does not move, we say that the car is stationary.

The car is moving, and we say the car is moving. For example, when the foot is not kicked out, the football is placed on the turf, it is stationary, and after being kicked out, the football is moving relative to the turf. Generally, junior high school students need to master an average speed, which is v=s t (distance divided by time).

Motion and rest are relative, depending on the reference you choose.

It is to see if one object is moving relative to another.

The states of motion of an object include rest and.

Motion, whereas motion includes the magnitude of the velocity and the direction of the velocity.

In a uniform circular motion, the state of motion is changed, because the direction of the velocity of the object has changedIn general, there are only two types of motion that remain unchanged.

One is stillness. The second is uniform linear motion.

In addition to these two cases, other sports, the state of movement will definitely change.

When an object is subjected to a non-equilibrium force, its state of motion is (changing). These include changes in velocity (magnitude), changes in motion (direction), and simultaneous changes in velocity (magnitude velocity) and (direction of motion).

Timely adoption, thank you!

1.On an east-west highway, there are two cars AB driving westward, car A is delayed faster than car B, and there is a certain interval, with the other party as a reference, car A moves westward, car B moves east; With the sun as a reference, both cars move towards the east of the code family.

2. Known: t=6s

t1 = 2sv1 = 6m hall digging s

t2=4sv2=3m/s

Solution: VSolution: S1=V1*T1=6m S*2S=12ms2=V2*T2=3M S*4s=12M

s=s1+s2=12m+12m=24m

According to: v=s t=24m 6s=4m s

3. Known: s=162km

v1=10m/s=36km/h

s1=72km

v2=45km/h

s2=162-72=90km

Solution: t1=s1 v1=2h

t2=s2/v2=2h

t=t1+t2=4h

According to: v=s t=162km 4h=

Velocity is a physical quantity that describes how fast or slow an object is moving, and its magnitude is equal to the distance traveled by the object in a unit of time.

v=s t In international units, the unit of velocity is meter seconds, which is pronounced as "meters per second" and the symbol is "m s".".

The linear motion that does not change the speed and auspiciousness is called uniform linear motion. An object that moves in a straight line at a uniform speed travels the same distance in an equal amount of time.

The linear motion of the velocity change is called the linear motion of variable speed. The change in the position of an object relative to the reference object is called mechanical motion.

Another object that is used to determine whether an object is moving or not is called a reference object.

Due to the different selection of references, for the same object, we can say that it is in motion or it is stationary. This property of mechanical motion is called the relativity of motion.

For variable speed linear motion, the formula v=s t can be used to roughly describe the motion of the object over a period of time, and this velocity is called the average velocity.

1m s 72 grade.

Let the elevator speed be V'The length of each step is s, and the total number of steps n, then there is:

When going upstairs, (2+v.)'*t1=ns 24s=2t1 when going downstairs (2-v'*t2=ns 72s=2t2 Synoid V'= 1m s n = 72 levels.

Equipment: stopwatch, meter ruler. Principle:

v=s/t。Steps: 1. Measure a distance of 100 meters and specify the starting and ending points.

2. Let Zhang Hong start running from the starting point, and record the time t1 at the start of the run, and then record her arrival time t2 at the end point. Calculate the time taken t=t2-t1.

3. Use the formula v=s t to calculate the speed.

A tape measure and a stopwatch are required, experimental principle: speed formula. Steps Textbook** - Measurement of average speed in this fuel-saving detailed step.

y1=16x1-（20+180）

y2=12x2-(5+192)

Judging an object when motion is still trembling is the method of rest

Solana is to select an object as the reference frame and observe whether the position between the object code spring body and the reference frame changes. If the position of the object changes, the object is in motion; If the position of the object does not change, the object is stationary.

(1) After the wick in the Kongming lamp is burned, the temperature in the lamp rises, the gas expands, and the density decreases, which is less than the density of cold air kg m3, and the Kongming lamp can be lifted into the air.

2) Density = Mass Volume =

3) Total mass = density and volume =

Increased mass

Principle: Because the fuel combustion in the Kong Ming lantern heats the air, the volume increases, so the buoyancy increases, so it can be lifted into the air.

f float = air density * lampshade volume * g =. f float - g lamp = g gas = gas = g gas g = . Air density in the lamp = approximately equal to.

Air quality inside the lamp = . m increase = m present - m original =

Inertia is an intrinsic property of all objects, whether solid, liquid, or gas, whether the object is in motion or at rest. Everything has inertia. Definition of inertia:

We call the property of an object that remains in constant motion inertia. Inertia represents how easy it is for an object to change its state of motion. The magnitude of inertia is only related to the mass of the object.

It is relatively difficult to change the motion state of an object with a large mass, that is, it has a large inertia; The motion state of an object with a small mass is relatively easy to change, that is, the inertia is small. When you kick the ball, the ball starts moving, and because the ball itself is habitually piercing and flat, it will keep rolling until it is stopped by an external force.

Any object has inertia at all times, and it has to maintain its original state of motion.