Chapter 7: Centripetal Force and Slingshot Magic
The hidden courtyard behind the abandoned west wing of the manor had become their secret sanctuary. Overgrown with ivy and shielded by high stone walls, it was the perfect place for a young lord and his attendants to break the laws of traditional magic.
Ren, now eight years old, stood before a massive, rotting oak stump that had been hauled in from the woods.
Elara and Kira sat on a wooden bench nearby, swinging their legs. They were dressed in their standard cotton training clothes, though Ren had secretly reinforced the stitching with a microscopic layer of carbon bonding to make them tear-proof.
"Standard offensive magic is tragic," Ren lectured, pacing in front of the stump like a tiny university professor. "If a traditional Earth Mage wants to cast Stone Bullet, they create a rock, put a massive wall of mana behind it, and push it forward."
Elara nodded eagerly. She was nine now, and her Earth Affinity was growing stronger by the day. "The tutor says it requires a high 'Burst' stat to make the rock go fast enough to do damage."
"Which is a terrible waste of energy," Ren sighed. "Pushing something in a straight line from a dead stop requires you to overcome all of its resting inertia at once. Why push when you can spin?"
He reached down and picked up a smooth pebble, no larger than a hazelnut.
"Watch carefully," Ren said.
He didn't chant. He simply held his hand out. Using a microscopic amount of wind magic, he suspended the pebble in the air above his palm. Then, he applied a tiny, continuous lateral force.
The pebble began to spin in a tight, horizontal circle. Slowly at first, then faster, and faster.
"Centripetal force," Ren explained over the growing hum of the spinning rock. "By keeping the object moving in a circle, we continuously build its velocity without needing a massive burst of energy. We just keep adding a tiny push to the rotation. The kinetic energy compounds."
The pebble was now a grey blur, vibrating with a high-pitched whine that made Kira’s fox ears flatten against her head.
"When the velocity is high enough," Ren smiled, his eyes locking onto the oak stump. "You simply remove the circular constraint."
Ren dropped the wind barrier holding the circle.
CRACK!
The sound was like a thunderclap. The tiny hazelnut-sized pebble shot forward at supersonic speed. It didn't just hit the oak stump; it punched a clean, smoking hole straight through the two-foot-thick wood and buried itself deep into the stone wall behind it.
Elara dropped her wooden training staff. Her jaw hung open.
Kira’s tail puffed out in shock. "Master Ren... you didn't even use a magic circle! The mana you used was so small I could barely feel it!"
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"Because the physics did ninety percent of the work, Kira," Ren said, dusting off his hands. "Now, it's your turn to apply it."
He tossed a leather sling to the fox-kin girl. It wasn't a magic item, just a simple strip of cured leather with a pouch in the middle.
"Kira, your Agility stat is phenomenal, but your raw strength and mana capacity are low," Ren analyzed. "You can't cast Stone Bullet. But with this sling, you can use your body’s natural rotational mechanics. Spin your arm, build the centripetal force, and release. If you coat the rock in a tiny layer of wind mana just to reduce air friction—"
Kira caught the sling. She loaded a smooth river stone, her amber eyes narrowing in focus. She didn't hesitate. She stepped forward, her lithe body twisting perfectly as she swung the sling above her head. One rotation. Two. Three.
She released it.
The stone shattered a smaller wooden target twenty yards away into splinters. Kira squeaked in delight, hopping up and down, her silver tail wagging frantically.
"Excellent," Ren praised, reaching out to pat her head. She immediately leaned into his hand, purring softly.
Ren then turned to Elara. "For you, my fierce Head Maid, the application is different. You have a high Earth Affinity. I want you to create a hollow, circular tube of stone in the air. Spin a rock inside it to build speed, then open one end and aim it."
Elara’s brow furrowed in concentration. She slammed her hands together. A ring of solid stone materialized in the air. She dropped a pebble inside and began pushing it with her mana, making it run laps inside the ring. It was harder to control than standard magic, requiring intense mental focus rather than raw power.
Sweat beaded on her forehead as the rock spun faster and faster, rattling inside the stone tube.
"Steady, Elara. Feel the momentum," Ren encouraged softly, stepping close behind her and gently guiding her arms.
With a shout, Elara opened the front of the ring. The rock blasted out, obliterating a terracotta pot on the far wall.
She slumped forward, panting heavily, but a massive, triumphant grin was plastered across her face.
"I did it!" she cheered, turning to Ren.
"You both did perfectly," Ren smiled warmly. He pulled a crystal flask from his satchel. Inside was a chilled, pale-yellow liquid.
"Drink this," Ren instructed, handing them each a small cup.
Elara took a sip and blinked. It was slightly sweet, a little salty, and incredibly refreshing with a hint of lemon. "What is this, Ren? It makes the tiredness in my muscles melt away."
"It's an electrolyte solution," Ren said smoothly. "When you sweat, you don't just lose water; you lose sodium and potassium. This replenishes your cellular balance instantly."
He pulled out a soft silk handkerchief and gently wiped the sweat from Elara’s forehead, then did the same for Kira. Both girls blushed deeply, their young hearts fluttering at his undivided, doting attention. In a world where nobles treated commoners and beast-kin like disposable tools, their young lord treated them like precious treasures.
As the girls drank their chilled "sports drink" in the shade, Ren looked at the massive hole in the oak stump.
His Skill Panel flickered subtly in the corner of his eye.
[Individual: Kira]
[AGI increased by +2]
[Individual: Elara]
[INT increased by +1]
[Earth Affinity Mastery increased]
The training was working. Their stats were growing far faster than the System's standard progression models allowed, simply because they were bypassing the inefficient 'leveling' system through applied science.
But Ren also noticed something else. The crack of the pebble breaking the sound barrier had been loud. Too loud.
If they keep advancing at this rate, we can't train above ground anymore, Ren calculated, his eyes drifting toward the heavy stone foundations of the manor. The noise and the kinetic impacts will attract the Baron's guards. Or worse, the Capital's spies.
He looked at Elara, who was happily sharing a piece of candied fruit with Kira.
I need a subterranean testing facility, Ren decided. And to dig out a massive underground bunker without anyone noticing... I'm going to have to get very creative with the plumbing.