Questions to prepare for the new physics class in the first year of high school

1) The second second refers to the time interval of 1 second from the end of the first second to the end of the second second. The numbers on the timeline all indicate the moment at the end of this second, for example, the point of 3 represents the end of 3 seconds, so the first second is the interval from moment 0 to the end of the first second, and the others are pushed back in turn.

2) If you count from the beginning, then 2s refers to the time interval of 2s length from the moment 0 to the end of the second second, that is, the point of 2.

3) According to the diagram, it feels like you are asking about the number between the second and the third second, which is the number 2, which indicates the moment at the end of the second second.

4) The points on the timeline (i.e., the red dots in the diagram) all indicate the end of the second or the beginning of the second, they are all moments, and time (also called time interval, usually omitting the word interval 2) is represented by the line segment between two points on the timeline. For example, the dot on the number 2, you can call it the end of the second or the beginning of the third second, which is a concept. But the second represents the line segment between 1 and 2 points.

1.The second s is just the point that refers to the 2s, which belongs to the moment.

2.Refers to the moment, within 0 2.

3.Count one second, no, it means from the second to the third.

4.The inequality is: n n+2

You can remember that pointing to a point is a moment, and referring to a paragraph is a moment.

1）.Does the second s just refer to 1s to 2s?

Yes, the time period from 1 to 2, just like day 2 refers to the time between the end of today and the end of tomorrow.

2）.So what does 2S mean?

It is the time of 2s, if you count from the 0th moment it means that it is from 0 to 1, 1 to 2, and if you start from 3, it is 3 to 4 and then to 5

3）.What is the point between 2s and 3s? Does it mean 2s, 3s, or more than 2 o'clock seconds?

I display the time, the moment at two o'clock!

4）.If you were told that it was 2s, and you were asked to find out the points that represented 2s, those were? (In the case of a range, it is expressed as an inequality with respect to t).

0

1, the 2nd refers to that moment, 2Within 2s refers to 1s to 2s

3。The point between 2s and 3s refers to one of the moments, more than two seconds.

Fourth, be clear.

It is recommended to use "Top Student Case" and "Breakthrough on All Fronts" in the Spark series. Both materials have different levels of difficulty, which are suitable for preparation, consolidation and improvement. Hope it helps!

Lightweight multi-crown Century Gold List etc., this category follows the course and is a relatively simple workbook.

I think it's okay, you buy Wang Houxiong, do the questions in the book when you preview, Wang Houxiong has the answer, and then do it at the same time when school starts.

Let the initial velocity be v0 and the acceleration be a, and when the continuous equality is t, the displacement of 1t is v0t at 2

The displacement after 2t is V02T A(2T) 2=2V0T+4AT2The displacement of 3T after weighing is V03TA(3T) 2=3V0T+9AT2

The displacement through n-1t is v0(n-1)t a((n-1)t) 2=(n-1)v0t+(n-1) at 2

The displacement through nt is v0nt a(nt) 2=nv0t+n at 2, so there is s1=v0t at 2

Displacement within 2t Displacement within 1t: S2=V0T 3at 23T Displacement within 2t: S3=V0T 5at 2So S=S2-S1=S3-S2=......sn-s(n-1) at The object at rest on the table is subjected to gravity and support, which is a pair of equilibrium forces.

Gravity is the gravitational pull of the earth on the object and the gravitational force of the object on the earth is a pair of action and reaction forces.

The support force and the pressure of the object on the ground are a pair of acting and reacting forces.

The first one, yes. Imagine a cylinder with pistons. A certain volume of gas is enclosed inside the piston.

Outside the cylinder is the atmosphere. Slowly push or pull the piston to increase or decrease the volume of the gas in the cylinder at the same temperature. Obviously, the gas will do external work in the process of increasing or decreasing the volume, and because the temperature of the gas does not change, that is, its internal energy remains the same, the gas will correspondingly release or absorb heat to the outside atmosphere.

Obviously, the temperature of the gas and the outside atmosphere is the same, so the condition of mutual heat transfer at the same temperature is satisfied. (The first law of thermodynamics is involved here, and the amount of change in internal energy is equal to the sum of work done and heat absorption, which is similar to the law of conservation of energy).

Second, there is a contradiction in this question. Since it is said that it starts from rest, when does it mean to find the speed of the ball? Does your answer mean that the ball is always moving at a uniform speed?

That's not the right thing to do. If we find the velocity of the ball at the fourth point where it is photographed, then we find a=(10 9)m s according to s=1 2*at 2,s=,t=. Therefore, I think that if you give a condition to a question, what you will seek will not be the answer above.

I can only think that the topic is wrong, that the condition of stillness is superfluous, and you are right. The answer to the question may be to take the first scale of 1cm as 0cm

1. The temperature of the object is the same, the internal energy is the same, and there can be no heat transfer (referring to natural transfer). But if there are external influences, it can be (e.g. chiller, work, etc.). According to the second law of thermodynamics:

It is not possible to transfer heat from a cold object to a hot object without other effects; It is not possible to take heat from a single heat source and convert it completely into useful work without other effects; That's it! As for the heat transfer you are talking about, you mean the self-repentant transfer.

In the case of workmanship, of course, it is possible to transfer heat to objects with the same temperature.

2. As for the second question you Wu Bi said, the athletic nature of the ball is lacking in orange (free fall?? I didn't say it, I couldn't solve it.

1.No, by the second year of high school, you will learn the second type of perpetual motion machine.

There is a very classic saying on 3-3: heat cannot be transferred spontaneously from a cold object to a hot object Attention! It can't be spontaneous! For example, the refrigerator is a workmanship that transfers heat from low temperature to high temperature, but the heat can never run from low temperature to high temperature by itself.

For example, the second type of perpetual motion machine is to concentrate the heat in the seawater to generate electricity, which is impossible, in short, it must follow the principle of conservation, in fact, imagine it.

It is not possible to absorb heat from a single heat reservoir and turn it into a complete function.

It does not produce a simple and coarse cover that has any effect.

I didn't understand the second question too well, and the first one you said was the initial stool cover or the second later? Does the ball move at a constant speed or at an accelerated speed? I don't know, maybe it's 6 meters.

1.No, the temperature is fine, and the difference in internal energy can only be achieved in order to have heat transfer. Just like the loss of sail current is required to generate voltage (potential filial piety difference).

t= v=s\t=20cm=

Friend, can you tell me what speed do you want at average speed? Instantaneous speed?

The meaning of this sentence is that the three forces are in equilibrium, and if they are not parallel, then the three forces (the extension line) are intersected at one point.

The balance of parallel forces, in addition to the balance of forces, also requires the balance of moments (the equilibrium force produces the moment, and the force * arm = moment).

If there are no parallel forces, then the three forces must be at the same point. To use the counter-proof method: if there is no common point, a moment will be generated, and the object with a strong moment will rotate and will not be balanced. Therefore, "the object is in equilibrium by three forces, and it is not parallel and must be at the same point".

This is determined by the fixed structure of the meaning and phrase.

Option b: The second word should be words. Word refers to information. If you use the word, then you should have appeared before to refer to it, how can you use the first time it appears?

If the class of the message is mentioned in the later dialogue, I think it will be fine to use the message again. Keep Ones Words, on the other hand, is a fixed structure, which means keeping promises.

The second question, all three have the meaning of sound, I didn't know it at first, and then I found a feature of them to remember, noises focus on noise, voices is a general term, similar to the general name of sound, and sound focuses on sound waves, which is a three-dimensional, something that enters our ears. So the meaning of this sentence, my understanding is that the sound wave of the sound I hear comes from television. Because this is a TV set, there is no emphasis on the sound as noise, so I use voice instead of noises

If the content of the question stem is that there is a working cutter outside, and its "sound" keeps me from sleeping, then use noises at this time

I haven't used English for three years, I don't know if the explanation is correct, I hope it helps you

1. No, just look at the beginning and end positions, for example, circular motion, exactly one turn in 2 seconds, then the average speed in these two seconds is 0Thought the displacement was zero. There's also the concept of velocity here:

The ratio of the distance traveled by an object to the time. Take care to distinguish between speed and rate. It's not the same concept as in junior high school.

2. There is no specific context, I guess it should be the average speed here, because it should be a period of time and a process in the tunnel. After all, it will take you some time to get through the tunnel.

3. First of all, it is clear that it is linear motion. Because you can only draw a V-T image in a straight line (because you want to specify positive and negative directions, you can only have two directions). The positive or negative of the oblique fiber rate indicates the direction of acceleration.

4. Same as above, but in linear motion. Hidden hail.

You should read more books.

1.Only the first and last positions are considered, whether straight or curved.

2.Tunnel rot is a length, is a displacement, not lead imitation is a position, so is the average speed.

3.Well, right.

4.As in the third question, Huai Tie Fiber is also correct.

There are two scenarios.

1.The force is opposite to the direction of velocity, i.e. b is not explained.

The definition of friction is related to the elastic force, which is the support force, and obviously the direction of f is a downward oblique elastic force.

FN=MG+FSIN F=UFN Select B When oblique upwards, elastic force FN=MG-FSIN F=UFN Select C

The formula of sliding friction f=un n is the interaction force between the object and the ground, and the force analysis of the object in the vertical direction: mg-n-fsin =0 So n=mg-fsin is f= (mg-fsin )

The key is which corner you are.

First, according to the sliding friction formula: f= n, the key is the magnitude of n, if the angle between f obliquely upwards and the horizontal plane is n=mg-fsin) c ;

If the angle between f diagonally downward and the horizontal plane is n=mg+fsin's b, if f is n=mg's a

There is no diagram that is not clear, it should be that the wooden block is moving at a uniform speed, which can be a slide or an upward movement. Two directions. Two answers, you can see for yourself.

The direction of the two forces is not the same, one obliquely upwards and the other diagonally downwards.