"Ding Yu ......" The melodious and rapid alarm clock rang.

Niu Zihao turned off the noisy alarm clock, and then continued to fall asleep.

"Sleep one more minute and then wake up!"

This minute is so short, and yet so long. By the time he woke up, it was already three hours later.

"Oops, overslept." Niu Zihao began to complain, "It must have been reading comics for too long last night, so I couldn't get up in the morning." I had no choice but to go to school and be criticized by the teacher. ”

He hurriedly rolled over and got out of bed, hurriedly brushed his teeth, washed his face, and went straight to the direction of school.

In the classroom, physics teacher Yang Junsheng banged on the podium and scolded angrily: "Look at your results in this monthly exam, there are 71 people in the class, and 8 talents with more than 60 points." As your substitute teacher, I feel like I'm about to see people out of sight. ”

"There are ......," it was obvious that Mr. Yang strengthened his tone, "I don't know how to take the test, but some students scored 13 points in physics." The 100-point question only scored 13 points, the multiple-choice questions were covered with a few questions, and although the fill-in-the-blank questions were written a few, they were all copied from the options of the previous multiple-choice questions, and the donkey's lips were not right the horse's mouth. The most infuriating thing is that the answer questions in the back did not touch a word. If you write a formula, the grading teacher will also be merciful and give you 1 or 2 points. Niu Zihao, with a score of 13 in physics, which one, stand up and let everyone know. ”

After speaking, the classroom was silent.

After a while, still no one stood up.

The students began to discuss, it can't be that the teacher took the wrong test paper, it may be an ordinary class, like the students in our key class, and they have to score more than 50 points in the test.

This Niu Zihao, but he is going to be unlucky, 13 points, I answered the test paper with my eyes closed, and it was also higher than this score.

……

Babbling, classmates, you keep talking about what you say, but no one wants to stand up. Besides, it's just started not long ago, and there are so many people in the class, who knows what Niu Zihao looks like?

Teacher Yang also smiled slightly embarrassed at this time, sure enough, Jiang is still old and spicy, that kind of laughter is similar to a skin smile and meat does not smile, and ordinary people can't detect it. As a teacher Yang who has been a vocational teacher for more than ten years, what kind of dilemma has he not encountered!

"The empty seat in the penultimate row in the middle, is it Niu Zihao?" Teacher Yang asked, looking at the empty seat.

"Yes, he may have taken a leave of absence today." Zhao Liyang, who was at the same table, stood up and replied.

"Excuse me, then it's up to you to go to the blackboard and do the questions, which is a bit similar to the 5th question in this monthly exam paper, but there is some improvement in the difficulty of the question type."

The hearts of the students below were pounding, but they lowered their heads, stared at the monthly exam papers in their hands, and at the same time breathed a sigh of relief, fortunately the teacher didn't call me.

When they were students, who wasn't afraid of the teacher's questions in class? Of course, there is one kind of exception - that is Xueba.

Some students have already taken out pen and paper, staring at the problem written by the teacher on the blackboard, and quickly looking for formulas in their brains that can be applied. As long as you can solve one type of problem, even if you can do ten or twenty more questions, you will be able to solve it easily. Some students couldn't even remember the formula, so they took out the palm treasure they bought in the bookstore and began to flip through it. Palm treasure, in fact, is a record of some of the necessary knowledge points in the book, because of its small size, can be read at any time, can also be carried, convenient and fast, by the majority of middle school students love.

Watching Zhao Liyang walk onto the podium, the classmates all held their breath, this little girl, will she solve this problem?

"Don't look at me, I won't!" The students below turned their heads and ears, turned the pen in their hands for a while, looked at their watches for a while, and finally locked their eyes on Zhao Liyang on the podium.

In the quiet classroom, the air seemed to have frozen at this time, and only Zhao Liyang's figure when solving the problem became the focus of attention of the audience.

A boy with glasses sitting by the window, the boss with his mouth open, could stuff an egg into it. The sun shone on his warm face, not wavering in the slightest as he looked at her solution. In his heart, it may no longer be a microwave, but a stormy wave. Beautiful, the way that girl looks when she solves the problem is very much like my love. Watching her solve the problem, there is quite a kind of "the leaves are pale, and the white dew is frost; The so-called Yi people, on the water side".

What no one will know is that the boy has secretly sworn that if Zhao Liyang solves this question correctly, then she will be the goddess in my mind in the future.

All the students, including Zhao Liyang himself, hope to solve this problem to prove that the key class is not in vain.

Zhao Liyang looked up at the blackboard and wrote:

If the car moves along a straight highway with an acceleration of 2m/s2, then in any 1s( )

A. Speed increased by 2 times

B. Speed increased by 2m/s

C. Displacement increased by 2m

D. Acceleration increases by 2 m/s2

Although the topic is very simple, only a few words, it involves the common physical quantities related to acceleration, velocity and displacement, and if you don't know how to use the formula reasonably, you may make mistakes.

The students below just stared at the blackboard, and none of them started to write, but there were a few who flipped through the books.

"Three long and one short choose the shortest, three short and one long choose the longest, this answer is not too long, I think choose C, who made it the shortest!" One student began to use his own problem-solving strategy.

"Nonsense, choosing C is pure blindness, I think it's D. There is a 2m/s2 in the question, and there happens to be a 2m/s2 in the answer. ”

Choose A, choose B, in short, there are 4 options to choose from, just as a thousand readers will have a thousand Hamlets.

Zhao Liyang took a serious look at the question, first of all, the answer D can be completely ruled out, and the key to doing uniform acceleration motion is the word "uniform", that is, the acceleration has always remained a=2m/s2 unchanged, but the answer D is a=4m/s2, wrong.

Acceleration is equal to the amount of velocity change per unit of time, which is judged by the definitive analysis of acceleration.

According to △x=aT2, the displacement increment in any 1 second was analyzed.

Answer C: According to △x=aT2, the displacement increases by 2m in any 1s, so C is correct.

In the same way, we can get the answer B: according to the definition of acceleration a=△v/△t, there is △v=a△t, so △v=2x1m/s=2m/s in any 1s, that is, the velocity increases by 2m/s in any 1s, so A is wrong, B is correct.

Looking at the solution ideas written by Zhao Liyang on the blackboard, Mr. Yang, who had been watching from the side, unconsciously glanced at it. This...... It's exactly the same as the correct answer, and even the idea of solving the problem is the same.

Looking at the students I teach, I can have such a mindset, which makes teachers very proud. "Alright, you go down."

The teacher's face also changed from cloudy to cloudy just now, and turned cloudy in an instant.

At this time, the voice of "report" came from the door.

"Niu Zihao, come in!"