Fang Chao's answer made the students in the second (fifth) class of high school laugh constantly, and even the physics teacher couldn't help laughing.

It is the first time he has met such a student in his teaching for so long, who is reasonable, bold and scientifically verified, and at this point, the other party has done it, and the so-called hypothesis is really a very bold idea, and at the same time, it is understandable on top of scientific proof.

Under limited conditions, the pressure changes instantaneously.

And the only two people who didn't laugh were probably Chen Chao and Zhang Yangyang.

At this time, the physics teacher said directly, "You came to the door of my class to listen to the class, it seems that you have a lot of ideas about physics, in that case, I will give you a question to see if you can do it." ”

The physics teacher didn't give Fang Chao a chance to answer or even turn away, he directly picked up a piece of chalk from the podium, and then turned around and quickly wrote some questions on the blackboard.

Fang Chao couldn't leave at this time.

Soon, one of the physics teacher's questions appeared on the blackboard.

"This classmate, you come up and answer this question."

The physics teacher looked at Fang Chao.

"Let you pretend to be forced, it's okay now, you're going to be embarrassed~"

"Mr. Zheng personally came up with the topic, and it is the person who interests him, this topic is interesting, it will definitely not be simple."

"If he knows, it's okay to say, if he can't, Mr. Zheng will go to his homeroom teacher, tsk......tt"

"This kid is quite tall, but he looks a little worse."

"It's not too ugly, it's just too peaceful, there's nothing particularly outstanding, the only thing that feels different, how to put it, is that there is a calm and unhurried self-confidence...... It seems like this. ”

"We haven't been exposed to Mr. Zheng's questions yet, where does this kid get his confidence? I don't believe he's going to ......."

“……”

Fang Chao took the chalk from the physics teacher's hand, and then stood in front of the podium to examine the topic.

Physics is an extension of mathematics, but it has more experimental procedures, and this is also the interesting thing about physics, using countless physics knowledge to derive the answers to physics.

The title is sauce purple:

A truck towing a compartment of the same mass, driving at a constant speed of V0=12m/s on a horizontal straight road, the resistance can be regarded as proportional to the weight of the vehicle, and has nothing to do with the speed. At some point, the carriage falls off and decelerates and coasts with an acceleration of a = 2 m/s2. After the carriage falls off t=3s, the driver realizes and brakes urgently, the resistance when braking is three times that of normal driving, assuming that the traction force before braking remains unchanged, find the distance between the truck and the compartment after they stop.

At first glance, this question looks the same as a math question, but a closer look reveals that it contains a lot of things that are different from math.

Mathematics is more inclined to geometry, mathematical formulas, and so on.

However, physical existence is based on reality.

What is Physics?

It is a discipline that studies the most general laws of the motion of matter and the basic structure of matter.

As a leading discipline in the natural sciences, physics studies the most basic forms and laws of motion of all matter, from the universe to elementary particles.

Its theoretical structure makes full use of mathematics as its working language, and experiments as the only criterion for testing the correctness of theories, and it is the most sophisticated natural science discipline today.

Therefore, as long as this question exists in reality, and a series of conditions are formulated, the answer to this question can be known.

However, in reality, Fang Chao couldn't own such a large truck, so he could only deduce.

Fortunately, Fang Chao raised the level of physics to LV2 when he entered high school, and in the process met the great physicist, Newton, so that he had a very deep understanding of Newton, and in the first semester of high school, he also taught himself part of physics.

Newton's achievements in mechanics are unparalleled.

And Newton's first law has long been deeply rooted in the hearts of the people, even if many people don't know what Newton's first law is at such a time, so when the words 'law of inertia' emerge, are they still confused?

This is the famous Newton's first law.

All objects always remain at rest or in a state of uniform linear motion, unless a force acting on it forces it to change this state.

Of course, because there is no such thing as an object that is not subject to force, Newton's first law is not an experimental law.

However, Fang Chao did not use Newton's first law, but Newton's second law.

The so-called second law is that the magnitude of the acceleration of an object is directly proportional to the force and inversely proportional to the mass of the object, and the direction of acceleration is the same as the direction of the force.

Various formulas are derived from this.

The physics teacher did not speak, and the students below were also thinking carefully and pondering, trying to deduce the answer to this question.

"He doesn't seem to be able to do it, he hasn't touched the chalk yet."

"I guess he just said it casually...... Physics, that's how it is......"

However, at the next moment, Fang Chao took two steps forward and began to write the answer on the blackboard surface that his right hand could reach in the upper left corner of the test question.

Solution: Let the mass of the truck be M, the ratio of the resistance of the car to the weight of the vehicle is u, the size of the truck traction force before braking is F, the size of the acceleration of the truck before and after braking is a1 and a2 respectively, and the gravitational acceleration is g.

Here, Fang Chao applied Newton's second law.

f2uMg=0

FuMg=Ma1

uMg=Ma

3uMg=Ma2

After the carriage is taken off, the distance traveled by the truck within t=3s is S1, and the final speed is V1.

v1=v0+a1t

v12=2a2s2

where s2 is the distance the truck slows down after braking.

Let the distance of the taxi after the carriage is s, and V02=2AS

△s=s1+s2s

△s=36m

Fang Chao finished answering, it took more than two minutes, less than three minutes.

Excellent, perfect solution steps and answers, Fang Chao is extremely satisfied with his answer this time.

The students below watched Fang Chao answer, those students who had started to write but paused for a little time in some steps had already been thrown away by Fang Chao, and by the time they figured out the key points, Fang Chao had already finished answering.

Everyone's eyes fell on the blackboard at this time, because they were not stupid, and this look seemed to be the case.

And......

O Nima!

How can a high school student write so beautifully?!!

Not to mention such a heavy study, most students face countless practice questions every day, even students who are good at writing in junior high school will be greatly discounted in high school, but the handwriting written by the male classmates in front of them is concise, but it is pleasing to the eye, even the physics teacher can't help nodding.