4:00 PM.
Shida Affiliated Middle School, Administration Building.
A small lecture hall on the third floor.
The afternoon sun was no longer as blinding as it had been at noon.
Golden light filtered through the hallway windows, casting long shadows on the floor.
The classroom was large.
But right now, only the six of them were here.
Six people.
The top six middle school students from the entire province’s physics competition.
Lin Yi had arrived early.
She was wearing a loose, short-sleeved shirt with a slightly faded graphic print.
Below, she wore a pair of baggy, washed-out jeans.
She had on a pair of canvas sneakers, but the heels were crushed down under her feet, worn like slippers.
Her hair was casually pulled back into a loose ponytail with a simple black elastic band.
She was slumped in the center seat of the front row.
She rested her chin in one hand.
In her right hand, she held a black gel pen.
The pen spun back and forth between her fingers.
Gazing at the leaves outside the window, she gave a bored yawn.
Footsteps echoed from the hallway.
Zhou Kai walked in, his backpack slung over his shoulders.
He habitually scanned the room, his gaze landing on the extremely relaxed figure in the center of the front row.
Zhou Kai froze for a moment, then his tense shoulders relaxed slightly.
He walked over.
"Captain."
Zhou Kai stopped two seats to Lin Yi’s right, pulled out a chair, sat down, and spoke.
Hearing his voice, Lin Yi stopped spinning her pen.
She turned her head lazily.
She looked at Zhou Kai, who was sitting ramrod straight, his posture so rigid that even the way he unzipped his backpack seemed meticulous.
Lin Yi chuckled.
"Well, if it isn’t Zhou Kai."
Lin Yi propped her cheek on her hand, her tone laced with familiar teasing.
"We’re at the provincial team training camp, so why do you still look so grim, like you’re about to charge into battle?"
"Relax a little. It’s not like the chair is a bed of nails."
Zhou Kai took a notepad and a fountain pen from his backpack, placing them on the desk.
He gave a wry smile.
"I’m not as carefree as you."
Lin Yi shrugged nonchalantly.
"Fine, you’re the one who’s going to be exhausted."
She turned her head away, slumped back into her chair, and resumed spinning her pen.
The others trickled in one after another.
Miao Shian sat down in the second row.
He Gui chose a seat in the farthest corner.
The last to enter...
...were the incessantly chattering Wang Huashao and Chen Zhuo, who was walking beside him.
Wang Huashao looked around as he walked, still rambling on about the food in the cafeteria.
He had originally wanted to pull Chen Zhuo to sit with him.
But Chen Zhuo walked directly to the front row and stopped in the seat to Lin Yi’s left, just across the aisle.
Lin Yi heard the footsteps.
She looked up.
Seeing Chen Zhuo, she offered a casual smile.
Then, she gave him a slight lift of her chin as a greeting.
Chen Zhuo nodded back at Lin Yi.
He then placed the pen and notepad in his hands on the desk.
Wang Huashao saw Chen Zhuo take a seat in the front row, then glanced at the casually dressed but undeniably imposing Lin Yi next to him.
He didn’t dare get any closer.
He conveniently settled into the seat in the second row, directly behind Chen Zhuo.
The classroom was silent.
No one was whispering to their neighbor.
In this environment, even the most active person, Wang Huashao, had clammed up.
A set of footsteps echoed from the hallway.
They were unhurried.
The soles of the shoes made a soft SHUFFLING sound as they scraped against the floor.
The door was pushed open.
An old man walked in.
He was about sixty-something.
His hair was graying and cut very short, close to his scalp.
He wore a faded old jacket, its zipper open to reveal a plain shirt underneath.
On his feet was a pair of old-fashioned Beijing cloth shoes.
In his hand, he held a chipped enamel mug.
The mug was large, with the red characters for "Labor is Most Glorious" printed on it, but the words were so worn they were barely legible.
His knuckles were slightly enlarged from years of holding chalk.
Professor Wang Yourong of Shida.
The man in charge of this provincial physics training camp.
And a true titan of immense seniority in the domestic physics competition circuit.
Professor Wang walked to the lectern.
He didn’t scan the room, nor did he offer any pleasant smiles.
THUD.
He slammed the enamel mug down hard on the desk.
It let out a dull thud.
The sound echoed through the spacious lecture hall.
That sound was like a signal.
The six students sitting below all tensed up slightly.
No roll call.
No opening remarks welcoming them to the provincial training camp.
No interactive session for everyone to introduce themselves.
Professor Wang simply turned around.
He faced the massive blackboard.
He took a piece of white chalk from the chalk box.
His wrist flicked up.
The chalk met the blackboard.
The sound of the chalk rapping against the board was like a machine gun firing.
Dense, crisp.
Without any pause or hesitation.
Professor Wang drew quickly.
He wasn’t drawing some fancy, complicated diagram.
He drew a common, middle-school-level circuit diagram.
A dry-cell battery pack, a switch, and wires connecting to a small DC motor.
A string was wound around the motor’s axle, with a wooden block suspended from it.
The diagram was too simple.
So simple that even a second-year middle school student just starting physics would recognize it.
After finishing the drawing...
Professor Wang marked the battery with voltage U.
He marked the motor with internal resistance R.
And he marked the wooden block with mass m.
He tossed the remaining chalk back into the box and dusted his hands.
He turned around.
"The problems you’ve done before, in your cities, in your schools."
Professor Wang’s voice was powerful and resonant.
"The wires have no resistance."
"The motor converts one hundred percent of electrical energy into mechanical energy."
"The pulleys have no friction."
He picked up the blackboard eraser and tapped the motor on the board.
"But I’m telling you, that’s a fairy tale."
Professor Wang looked at the six middle school students below.
"The National Junior Applied Physics Contest tests you on the word ’applied.’ It tests you on the real world."
"In the real world, there are no absolutely ideal models."
He unscrewed the lid of his mug and took a sip of water.
Then he pointed a finger at the diagram on the blackboard.
"This motor is used to lift this wooden block."
"Now, I’m going to increase the mass m of the block infinitely, to the point where this motor can’t turn it at all."
"In layman’s terms, the motor is stalled."
Professor Wang’s tone shifted.
"Your textbooks taught you that electrical power P = UI. As long as there’s a current, it’s doing work."
"But I’m telling you now, if the motor is stalled, it will start smoking and burn out if the current runs for more than ten seconds."
He paused, looking at the boys in the front row.
"Why does it burn out?"
"Why doesn’t it burn out when it’s spinning, but it does when it’s stalled?"
As soon as he spoke these words...
Zhou Kai’s brow instantly furrowed.
Wang Huashao opened his mouth as if to say something, but after mentally running through every formula from his middle school textbook and finding none that could explain the phenomenon, he shut it again in disappointment.
"During this half-month training camp..."
Professor Wang’s voice echoed in the spacious classroom.
"I’m going to shatter every single one of those fairy tales in your heads."
"I want you to learn to consider the back electromotive force generated when the motor rotates, to consider how much energy becomes Joule heat while the rest is converted into mechanical energy."
Professor Wang raised his wrist and glanced at an old Shanghai-brand mechanical watch.
"First placement test."
"Close the switch. The wooden block rises at a maximum constant velocity v."
"Don’t just plug and chug with those incomplete formulas from your middle school textbooks."
"Using the principle of conservation of energy, I want you to derive the algebraic expressions for this motor’s actual output power and the block’s ascent velocity v."
He lowered his hand.
"You have thirty minutes."
"This problem isn’t beyond the curriculum. It only uses the most basic knowledge of middle school electricity and mechanics."
"But the prerequisite is that you have the guts to overthrow the standard answers your teachers taught you."
"Begin."
The moment he finished speaking...
The air in the classroom seemed to be sucked dry.
A pure, merciless, academic beatdown from a higher dimension descended upon them.
There was no yelling.
No threats.
Just a very common, everyday phenomenon.

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