Chapter 29: Forty-Five Minutes in the Stairwell

9:30 p.m. The lights-out bell rang.

The iron striker hit the brass bell. The sound was dull, echoing. The fluorescent tubes in the corridor flickered twice, then went completely dark. Rustling came from the dorm room as people turned over in bed. Someone tugged at a blanket. Someone coughed softly. The air temperature dropped fast.

Lin Chen did not move. He lay flat on the top bunk, his hands folded over his abdomen. He slowed his breathing, pressed one ear against the bedboard, and listened to the sounds in the hallway.

9:35 p.m. The night patrol teacher’s leather shoes approached from the stairwell. Even rhythm. They stopped outside Room 402. A flashlight beam swept under the crack beneath the door. The patch of light lingered on the wall for three seconds, then moved away. The footsteps continued onward.

9:38 p.m. The sound vanished at the far end of the corridor.

Lin Chen opened his eyes. No hesitation. He threw back the blanket with the lightest movement. His feet touched the floor. The gauze over the crack in his sole rubbed against the inside of his shoe, and a sharp pain shot through him. He held his breath, leaned his weight forward, and avoided the creak of the bed frame.

He felt around for his canvas bag, pulled open the zipper, and took out half a candle, a box of matches, a piece of cardboard, a notebook, a pencil, a ruler, and an eraser, slipping each item into his coat pockets one by one. He pulled the zipper all the way up without letting the metal clink.

He walked to the door, gripped the handle, and slowly pressed it down. He eased the door open just enough to slip through sideways, then pulled it shut behind him. The latch clicked softly into place.

The corridor was dark. Only moonlight filtered in from the window at the far end. The terrazzo floor gave off a cold sheen. He kept close to the wall, placing each step on the seams between the floor tiles, avoiding the standing water, his center of gravity kept low, his breathing steady.

At the turn in the stairs between the fourth and third floors of Building Three, there was a half-open ventilation window. Outside it stood the boiler room chimney. The night patrol route never came this way. A blind spot for surveillance. He had confirmed it three times.

He reached the corner and stopped. His back against the wall, he listened. Only the wind. And, from the distant athletic field, the dry rustle of cinders being blown across the ground.

He crouched down and took the piece of cardboard from his pocket, laying it flat on the floor. He stood the candle in the middle of it, struck a match, and the flame leapt up. Shielding it with his hand, he lit the wick, then blew out the match.

Wax dripped onto the cardboard and hardened at once. The candlelight steadied, illuminating a radius of about half a meter: the damp stains on the wall, the dust on the floor, the pages of his notebook.

He opened the notebook to a blank page, spread out his physics workbook, and turned to Question Ten.

Given: the incline angle is θ = 37°. The object has mass m = 2 kg. The coefficient of kinetic friction is μ = 0.25. A pulling force F acts upward along the incline. Find the range of critical pulling force for which the object is just prevented from sliding.

He picked up the pencil and drew a coordinate system on his scratch paper, marking gravity, the normal force, friction, and the pulling force. He resolved gravity into components: Gx = mgsinθ. Gy = mgcosθ.

He wrote down the equations. When the object tends to slide downward, friction acts upward along the incline. F + f = Gx. f = μN = μGy. Substituting the values: F + 0.25 × 2 × 10 × 0.8 = 2 × 10 × 0.6. F + 4 = 12. F = 8 N.

He paused and checked. The logic held.

When the object tends to slide upward, friction acts downward along the incline. F = Gx + f. F = 12 + 4. F = 16 N.

He wrote the conclusion. Critical range: 8 N ≤ F ≤ 16 N.

The pencil point scratched softly over the paper. His fingers had gone stiff with cold, his knuckles aching. He set the pencil down and cupped his hands over the candle flame to warm them. Heat touched his skin, bringing a faint sting as the blood returned. He rubbed his finger joints, then picked up the pencil again.

Second question. If the pulling force F = 10 N, determine the object's state.

He paused and did not rush into an acceleration formula. 10 N lay between 8 N and 16 N. Static friction had not yet reached its maximum. The object remained at rest. Acceleration was zero. The actual static friction was 2 N, directed upward along the incline.

He checked it again: range, signs, units, direction. No mistakes.

He flipped to the math workbook and turned to the final trigonometry problem. Given sinα + cosα = 1/5, and α ∈ (π/2, π), find tanα.

He wrote: Square both sides. sin²α + cos²α + 2sinαcosα = 1/25. 1 + 2sinαcosα = 1/25. sinαcosα = -12/25. Combining this with sinα + cosα = 1/5, solve the system. Let sinα = x, cosα = y. x + y = 1/5. xy = -12/25. x² - (1/5)x - 12/25 = 0. 25x² - 5x - 12 = 0. (5x - 4)(5x + 3) = 0. x = 4/5 or x = -3/5. Since α ∈ (π/2, π), sinα > 0 and cosα < 0. Therefore sinα = 4/5, cosα = -3/5. tanα = -4/3.

He put the pencil down and rubbed the space between his eyebrows. His eyes were dry and sore. The candle flame flickered, stretching and shrinking the shadow on the wall.

He looked at the candle. Only one centimeter remained. Wax had pooled around the edge of the cardboard. It had about fifteen minutes of burn time left.

He opened his ledger and moved the pencil across the page. Day 8. 22:15. Calculations in the stairwell. Progress: Physics Question 10 completed. Final math problem completed. Time spent: 45 minutes. Status: Target met.

The pencil tip paused. He closed the ledger, fingers tightening slightly. The page edges had begun to curl.

Footsteps came from the corridor.

Very light. But the rhythm was off. Not the night patrol teacher’s leather shoes. Rubber soles, scraping faintly against the floor. The sound stopped at the stairwell.

Lin Chen held his breath. His fingers swiftly pinched the candlewick and snuffed it out. The light vanished. Darkness swallowed the corner instantly.

He pressed himself flat against the wall, body lowered, clutching the canvas bag to his chest. He made his breathing as shallow as possible.

The footsteps came closer and stopped above the turn in the stairs. A flashlight beam swept downward, skimming past the ventilation window, the wall, the floor, then stopping on the cardboard.

“Who’s there?” The voice was young, cautious. A student union dorm inspector.

Lin Chen did not answer. He slipped a hand into his pocket and touched half an eraser. Gently he set it on the floor and nudged it with the tip of his shoe. The eraser rolled down the stairs, making a faint tapping sound.

The flashlight beam immediately swung downward. The footsteps followed after it.

Lin Chen waited. Counted to thirty.

He struck another match and relit the candle, moving fast. He packed the notebook, workbook, pencil, eraser, and ruler back into the canvas bag one by one, zipped it shut, blew out the candle, folded the cardboard, and stuffed it into the side pocket of the bag.

He stood up, leaned his weight forward, and moved quickly toward the fourth floor with his shoulder brushing the wall. His steps landed on the tile seams without making a sound.

9:55 p.m. Outside Room 402.

He gripped the doorknob, slowly pressed it down, opened the door, and slipped inside sideways, pulling it shut behind him.

The dorm room was very quiet. The boy on the lower bunk was breathing evenly. The two by the window turned over, their blankets scraping against the bedboards.

He walked to his bed, set down the canvas bag, and took off his shoes. The crack in his sole had been soaked through with sweat. The edges of the gauze had turned dark. He did not touch it. He only rested his feet on the edge of the bed and let them air out.

He lay down and closed his eyes. In his mind he arranged tomorrow’s schedule. Six-thirty: morning self-study. Seven: breakfast. Eight: classes. Twelve: lunch break. Six-thirty in the evening: evening study session. Nine-thirty: back to the dorm. Wash up. Sleep.

One step, one footprint.

Outside the window, the wind had died. Moonlight lay across the cinder track. Puddles reflected a cold gleam.

He placed his hands on his knees and slowly flexed them. The pain in the soles of his feet had already gone numb. His body felt hollowed out. But he did not sleep. He placed his hands on his knees and slowly worked them.

The next morning. 6:20 a.m.

Lin Chen opened his eyes ten minutes early. No transition. His mind cut straight from light sleep into wakefulness. After a night of drying, the crack in his sole had scabbed over again. When he turned over, it tugged at his ankle, and sharp pain flashed through him, but it was manageable. He held his breath and slowly sat up. The dorm room was quiet. The boy on the lower bunk was still asleep. The two by the window were already up, folding their blankets. The air smelled of mothballs and old wood.

He felt for the canvas bag by the head of the bed: ledger, pencil, half an eraser, ruler. He counted each item and lined them up in order. His movements were slow, but extremely steady.

6:25. He pushed the door open. The corridor was paved with terrazzo, worn smooth and glossy around the edges. Morning light slanted in from the window at the far end, falling across the duty roster posted on the wall. He walked close to the wall, leaning forward, avoiding the puddles gathered in the seams between the tiles. In his head he arranged the timing: from Building Three to the washroom, fifty meters. Walking, two minutes. Washing up, five minutes. Back to the dorm, get the lunch tin, go to the cafeteria, ten minutes. 6:50, arrive at the classroom. Morning self-study.

Wind crossed the cinder track, lifting fine gray dust. His fingers were numb with cold, the joints stiff and sore. He tucked his hands into his sleeves and rubbed them in turn. He could not stop. If he stopped, his body temperature would drop too quickly. In his head he was doing the math: balance, 1.56 yuan. Meal tickets, five days left. Sixty cents a day. Study materials fee already paid. The figures in the ledger had to fit exactly, without the slightest gap.

6:35. Washroom. Tin faucets. The stream of water was thin. He filled a basin with cold water. It was piercingly cold. He plunged his face into it and held his breath. Ten seconds. Then he raised his head. Water droplets ran down his chin. He picked up the towel and dried his face quickly, not wasting the warmth left in the water.

6:40. Cafeteria. A low red-brick building. A long line stretched outside the entrance. Above the serving window hung a wooden sign: Vegetable dish: 0.15. Meat dish: 0.40. Rice: 0.05. Soup: free.

Lin Chen stood at the end of the line. In front of him was a boy in a dacron shirt holding an aluminum lunch tin. Behind him was a girl with a ponytail reciting vocabulary under her breath. He lowered his head and looked at his own canvas shoes. The uppers were split. The soles were worn flat. The edges of the newly nailed-on patches had already started to curl up.

6:45. His turn.

“One vegetable dish. One serving of rice.” He handed over his meal tickets.

The server gave him a glance. The ladle shook once. A spoonful of cabbage, with very little broth, went into the aluminum tin. Then another scoop of rice, pressed down firm, was added and passed across the counter. “Next.”

Lin Chen took it and murmured thanks. Then he turned and walked to a long bench in the corner of the cafeteria and sat down. He opened the lunch tin. Steam rose, carrying the earthy smell of cabbage. He picked up his chopsticks and ate very slowly, chewing thoroughly until there was something solid in his stomach.

He did not drink the soup. Soup filled the stomach but did not keep hunger away. He divided the rice in the lunch tin into two portions. He ate one and saved the other, wrapping it in oiled paper and placing it in his canvas bag for lunch.

The figures in the ledger had to fit exactly, without the slightest gap.

7:00. The preparatory bell for morning reading rang.

The flow of people in the hallway began to reverse. Footsteps grew heavier. Voices dropped low. Lin Chen slung the canvas bag onto his back, pushed open the door, and walked into Class 1-3.

More than thirty students were already seated in the classroom. The fluorescent tubes gave off a faint buzzing sound. The air smelled of old books and sweat. He walked to the last row by the window and sat down, sliding the canvas bag into the desk compartment and keeping one hand pressed on it.

7:05. Morning self-study officially began.

Uneven recitation rose through the room: English vocabulary, classical Chinese texts, physics formulas. Lin Chen did not read aloud. He opened the physics workbook to Question Ten and reviewed the solution steps from last night. The logic was clear. The process complete. He picked up his pencil and wrote in the blank space: Core of the hardest problem: critical state. Maximum static friction. Simultaneous equations.

The boy in the front row turned around, holding a folded exam paper. “Hey, new guy. Friday’s monthly exam. This is last year’s paper. Two-hour time limit. Give it a try.”

Lin Chen looked up. “Thanks.”

The boy placed the exam on his desk. “Don’t copy the answers. Time yourself. It’s normal if you can’t finish. The county school average was only seventy-five.”

Lin Chen lowered his head and looked at the paper. The page had yellowed, its edges creased. Question One: basic force analysis. Question Two: incline and pulley. Question Three: critical friction. Question Four: integrated final problem. He picked up his pencil and drew a coordinate system on the scratch paper.

8:00. The class bell rang. The iron striker hit the brass bell. The sound was dull, echoing.

He opened his eyes, sat up straight, opened his math textbook, and lowered the pencil tip to the paper, ready to take notes.

Footsteps came from the corridor, drawing closer.

The physics teacher entered the classroom carrying a stack of papers. Chalk dust clung to his cuffs. He set the papers on the lectern and clapped his hands once.

“Quiet.” His voice was not loud, but the classroom fell silent at once.

“Friday’s monthly exam. Scope: the first three chapters of mechanics, trigonometric functions, oxidation-reduction, and classical Chinese content words.” The teacher paused, his gaze sweeping across the class. “This time, the scholarship criteria have been adjusted.”

A faint intake of breath passed through the room. Some students tightened their grip on their pens. Some lowered their heads to look at their toes.

“The grade office has issued notice. First-prize scholarship spots have been reduced from five to three. The score cutoff has been raised from the top thirty percent of the grade to the top twenty percent.” He picked up the chalk and wrote on the blackboard: 20%.

“If you don’t reach it, you don’t get evaluated. If you need a make-up exam, there will be no make-up payment. Judge for yourselves.”

The chalk snapped and fell to the floor with a crisp sound.

The teacher turned around and began passing out papers. “Today we’re covering force analysis. Open your workbooks to page twelve.”

Lin Chen lowered his head and looked at the number on the blackboard. 20%.

He opened his ledger and moved the pencil across the page. Day 9. 08:10. Monthly exam rule change. Scholarship slots: 5 → 3. Score cutoff: 30% → 20%. Strategy: zero mistakes on the basic questions. Get partial credit on the final problems. Total score must be ≥ 85. Funds: balance 1.56. Meal tickets remaining: 4 days.

The pencil tip paused. He crossed out “≥85” and wrote beside it: ≥88.

He closed the ledger. His finger joints were stiff. He placed his hands on his knees and slowly flexed them. Inside his Liberation shoes, the newly nailed sole patch pressed against the crack in his foot. Painful, but still weight-bearing.

Outside the window, the wind had stopped. Sunlight lay across the cinder track. The chalk marks, written as scales, glimmered faintly in the shade.

He closed his eyes. In his mind he arranged the schedule. Eight: class. Twelve: lunch break. Six-thirty in the evening: evening study session. Nine-thirty: back to the dorm. Wash up. Sleep. Tomorrow, six-thirty: morning self-study.

One step, one footprint.

He picked up the pencil and opened the workbook to page twelve. Question One. Force analysis. He drew a coordinate system and marked gravity, the normal force, and friction. The pencil tip moved over the paper with a soft scratching sound.

Footsteps came from the corridor, drawing closer.

Old Li, the physics teacher, entered the classroom carrying a stack of papers. Chalk dust clung to his cuffs. He set the papers on the lectern and clapped his hands once.

“Quiet.” His voice was not loud, but the classroom fell silent at once.

“The rules have changed. The number of problems will not shrink. All you can do is hold on to every point you already know how to earn.” Old Li turned and wrote four words on the blackboard: critical conditions.

Lin Chen lowered his head and copied the range he had just calculated into his wrong-problem notebook. Eight to sixteen. Not a single answer. A range in which the object could still exist. If the pull stayed inside it, the object did not move. Only above the upper bound or below the lower bound would it begin to slide.

He suddenly understood. The scholarship was also a range. Effort did not guarantee an outcome. The cutoff had risen. The number of places had narrowed. Everyone had been pushed into a tighter critical interval. Whoever made one fewer mistake could stand there a little longer.

Outside, the sky was beginning to darken. The clouds hung low. White smoke poured from the distant chimney. The wind carried the damp, earthy smell of soil.

It was going to rain.

He closed the ledger. His finger joints were stiff. He placed his hands on his knees and slowly flexed them. Inside his Liberation shoes, the newly nailed sole patch pressed against the crack in his foot. Painful, but still able to bear weight.

The dismissal bell rang. Students began to stand. Chairs scraped against the floor. Exam papers were rolled up. Someone muttered about the reduced scholarship slots. Someone asked Old Li whether the final problem would be beyond the syllabus.

Lin Chen did not crowd forward. He shouldered his canvas bag and walked out of the classroom close to the wall. The corridor was heavy with damp air. The terrazzo floor reflected a dull sheen. At the stairwell turn he stopped for one second and looked toward the place where he had hidden the night before. The cardboard and wax had both been cleared away. No trace remained.

No trace. That was safety.

He continued toward the dormitory. In his mind he rearranged time. Twenty minutes of noon rest. Chemistry medium conditions in the afternoon. Last year's real paper during evening study. After lights-out, no more than forty-five minutes of risk. Only a stub of candle remained. Only six matches remained. Every one had to be used on the blade's edge.

One step, one footprint.