The next morning, the traveler—who now allowed Luma to call him "Elder Ion"—led her to a quiet riverbank where stones rested undisturbed under the morning mist.
"Today," he said, picking up a small rock, "we learn why things move—or don't."
He set the stone on a flat log.
"Now watch," he said, and stepped back.
Nothing happened.
Luma raised an eyebrow. "It's just sitting there."
"Exactly," Elder Ion said. "Objects stay still unless something makes them move. This is called inertia. It's part of the First Law."
He gave the log a gentle push. The log shifted—and the stone tumbled off.
"It moved because I applied a force," he said. "No push, no motion. And it works the other way, too."
He picked up the same stone and tossed it gently down the slope. It rolled, then slowed, then stopped.
"Why did it stop?" he asked.
"The ground and grass slowed it down," Luma answered.
He smiled. "Friction. A force that resists motion. If there were no friction or air, the stone would keep going forever."
Luma's eyes widened. "So… things don't want to move or stop—they just follow forces?"
"Exactly," he said. "Everything keeps doing what it's doing—unless a force changes it."
She looked at her own hand. "So even me… I'm always being moved by something?"
"In the Realm of Physics," Elder Ion said, "even your heartbeat follows the laws. And understanding those laws… is power."