Teacher Xu, Please Take Care of the Reckless Students in Your Class

"Hiss..."

"Hs...hs..."

What's the matter with him? !

Dong Mengshan raised his head and looked at the three invigilators, who were standing next to a candidate.

Those three candidates seemed to be from Yunhu No. [-] Middle School.

Dong Mengshan, "!!!"

At this time, not only Dong Mengshan, but other candidates raised their heads one after another, and noticed the abnormality of the three invigilators.

"what happened?"

What else can happen!

The candidates of these five middle schools have all completed the third question, and they have even finished the fourth question!

How could they not be surprised? !

How is it possible not to be shocked? !

If one person is an exception, the candidates of No. [-] Middle School are doing it very fast!

What's worse, they all seem to be from the same class - the second (30) class of Yunhu No. [-] Middle School!

rely on ...

Originally, with Dong Jianshan's answering speed, it was already very fast, and the speed of other candidates was normal.

Who put them and Qian Mengmeng in the same exam room?

Compared with them, let alone Dong Jianshan, who was the second silver medalist, even the first gold medalist would only be killed in seconds in front of them!

Although Wei Minghai and the others are not as terrifying as Qian Mengmeng, the third question gave two ways to solve the problem, but they have already started to do the fourth question!

In half an hour, they had already completed the fourth question with impeccable momentum.

Including Li Jingyi...

Li Jingyi, who raised his head and glanced at the time, was stunned.

After a few seconds of delay, he couldn't help but muttered, "Damn, why did it only take half an hour?".

104 Simple as that!It's not too much to turn in the papers two hours in advance, right? ! [5 more!Two in one!Please subscribe! ]

The fourth question:

In the plane rectangular coordinate system S that is stationary relative to the laboratory, there is a photon, which shoots an electron stationary at the coordinate origin O along the positive direction of the x-axis.

A scattered photon is detected in the y-axis direction.

It is known that the rest mass of the electron is 0 m, the speed of light is c, and the difference between the energy of the incident photon and the energy of the scattered photon is equal to 1/10 of the rest energy of the electron.

1.Try to find the magnitude v of the electron's motion speed, the angle θ between the direction of the electron's motion and the x-axis; the time it takes for the electron to move to point A with a distance of 0L from the origin (as a known quantity) Δt. ?

2.When the electron starts to move at the speed v in 1, an observer S' relative to the coordinate system S also moves in the direction of the electron movement in S at the speed v (that is, S' is stationary relative to the electron), try to find S' to measure The length of the OA.

Qian Mengmeng has three ideas for the third question, so she is only doing the fourth question now.

Li Jingyi caught up with the progress and was ready to do the fourth question.

But when he raised his head and looked at the time, he was stunned!

In the past, every time he took the test and completed the third question, half of the time had passed, even nearly two hours, but this time, it was something Li Jingyi never expected-.

However, in the process of this exam, Li Jingyi clearly felt that he was very handy.

In the past, when I read the question, I read it several times, and pushed the process on the performance paper before I dared to write it on the test paper. Now, after reading the question, Li Jingyi thought for a while, and he had a clear idea in his mind.

"call……"

"unexpected."

Li Jingyi was extremely excited, slowly lowered his head, and continued to read the question.

Before he came to class 30, he always felt that the physics competition made him more and more like walking on thin ice, but now, he seems to be at ease and uncomfortable.

Continuing to read the question, the corner of Li Jingyi's mouth rose slightly.

be happy!

At the same time, I also think that these questions are not as difficult as you think!

Picking up the papier-mâché, he wrote and drew, and soon came to an answer.

"Forehead……"

Even Li Jingyi was stunned. He didn't expect that he would calculate a process on paper and give the correct answer directly!

The first question: 2.4L0/c.

Second question: L0.

Write the answer directly?

Li Jingyi didn't dare to procrastinate, so he rethought his thoughts and finally copied the answer.