Chapter 28: Why Does This Examinee Laugh?

"First, establish a spatial Cartesian coordinate system, then use the centroid formula to determine the position of the teacup's center of mass."

For Xu You, who was proficient in mathematical competitions, such operations were far too basic.

In less than a minute, Xu You had calculated the coordinates of the teacup's center of mass in that coordinate system.

"Just need to make the height of the teacup's center of mass as close to the surface of the stool as possible."

Within three minutes, Xu You had solved the first question.

The second question involved the force analysis of solid objects.

Xu You quickly determined the cutting plane and transformed it into planar force analysis.

Using trigonometric relationships and conditions for torque balance, he formulated several equations.

"By combining equations 7, 10, and 11, the final change in force can be calculated."

In less than ten minutes, Xu You had completed the entire process for the first question.

Considering the 3-hour exam duration, the time allocated for each question was roughly just over 20 minutes.

Xu You's speed set a good precedent for this exam.

This was the key difficulty of the semifinal round.

Many questions could be solved by the examinees if given enough time.

The challenge, however, was completing them within the allotted time.

By the time Xu You finished the first question, some students were just starting to establish their coordinate system, or even unsure how to calculate the center of mass height.

This was largely due to their insufficient mathematical knowledge.

Having time to prepare for one competition subject outside of regular high school studies was already quite difficult.

Few students, like Xu You, were able to prepare thoroughly for two competition subjects simultaneously.

The second question, a relatively simple geometrical optics problem, was of course, for Xu You.

It could be solved using the principle of equal optical paths, a fairly routine topic.

The difficulty of questions three and four was not too high, but they required a bit more computation, with Xu You spending no more than twenty minutes on each.

Questions five and six clearly became longer, giving off a vibe reminiscent of the IPhO and APhO without careful inspection.

For example, question five involved the concept of laser cooling, typically seen in IPhO and APhO problems.

However, upon a thorough reading, one would find that laser cooling was merely mentioned in passing, with the focus being on the Doppler effect of light and resonant absorption.

After completing the first six questions, Xu You checked the time and found he had more than an hour left.

This pace was even faster than he had planned, giving him ample time to tackle the last two major questions, which were often the most difficult.

Other students, the faster ones, had just reached question five.

The slower ones were just starting on question three, not including some parts they had skipped.

Of course, many students in the semifinals were completely overwhelmed by the questions and chose to leave the exam early.

They had to admit that competitions were not their battlefield.

They were just slightly better than average in high school physics and would be better off focusing on their college entrance exams.

"Question seven isn't that hard, actually."

It was a dynamics problem, focusing on the force analysis of rigid bodies.

The thought process was of medium difficulty, with the calculation volume being somewhat large.

Xu You listed more than twenty formulas for the three sub-questions.

Although calculators were allowed in the physics competition, Xu You performed some of the simpler calculations by hand.

This was a strategy he had developed: unless dealing with very large numbers or complex equations, manual calculation could be more convenient than using a calculator.

In twenty-five minutes, Xu You had completed the entire process for question seven.

With over forty minutes left to solve the last question, he had plenty of time to spare.

The final question, a dynamics problem on electromagnetic induction, required the examinee to set appropriate parameters for calculation.

The problem itself wasn't very innovative; the difficulty lay in the cumbersome process and large amount of calculation required.

However, thirty minutes later, Xu You had smoothly completed it.

After solving the last data point, Xu You could finally take a deep breath.

The semifinal exam was indeed challenging, far more so than the preliminary round, with increased difficulty.

The only downside was that the questions seemed a bit outdated and formulaic, lacking creativity.

It appeared that the examiners had mostly taken old questions, made minor modifications, and compiled them into the exam paper.

If Xu You had the chance to set questions in the future, he certainly wouldn't be so hasty.

Ideally, he would create questions not found in textbooks, as those would be more interesting.

Imagining the scene of examinees cursing him behind his back, Xu You felt a perverse pleasure.

"Why does this child seem to be smiling?"

The invigilator also noticed Xu You.

Among the many distressed examinees, Xu You stood out

 for his relaxed demeanor, seemingly amused by something.

With curiosity, the invigilator walked over to Xu You and reviewed his exam paper.

Surprisingly, every question was thoroughly answered.

"This level, he should be able to get a top provincial rank, right?"

The invigilator finally understood Xu You.

If it were themselves, having answered such a difficult exam paper so well, they would probably be laughing too.

Of course, Xu You's relaxation was brief, just a moment of mental respite after completing the paper.

He immediately began to check his work seriously.

For such an important exam, Xu You wouldn't consider handing in his paper early without being certain of his answers.

At noon, the exam ended with the ringing of the bell.

Many students had not noticed the passage of time and had to hurriedly stop writing and submit their papers.

After the collection, the exam room was filled with lamentations.

"I'm done, could I actually score zero in the semifinals? I'm not sure about any of the major questions."

"I think my brain is fried; I can't even remember what I wrote just now."

"I didn't solve half of the questions; I guess there's no need to prepare for the practical exam. That's fine too."

Xu You, of course, did not join in the pointless complaints and walked straight out of the exam room.

He was waiting to compare answers with Hu Shucheng.

This time, Hu Shucheng had not handed in his paper early either.

They met outside by chance.

"You didn't hand in early this time?"

Seeing Hu Shucheng in the corridor, Xu You asked with a smile.

"This time, I couldn't afford to be careless. The theory and practical exam scores are cumulative, and every point is crucial. Let's go to McDonald's to compare answers!"

Given the increased difficulty of the semifinal questions, a mere verbal comparison wouldn't suffice to clearly reconstruct the entire solving process.

It would be better to find a place and replicate the answering process.

"Okay, my treat!"

"Then I won't be polite."

To thank Hu Shucheng for his guidance in the practicals, Xu You naturally wanted to treat him to a good meal.

"Just get us two 1+1 deals."

"Hey, I'm treating; let's get something more expensive."

Xu You, not sparing any expense, ordered two deluxe cheese thick beef burger meals and added a side dish.

As they ate, they reconstructed the solving process of the exam.

(End of Chapter)