Physics Tricks

Lin Chuan and Terai said nothing throughout the night. Neither wanted to talk, so they slept in the trees. Nothing unusual happened last night. It seemed everyone had been worn out by the instructor's torment. With such a rare chance to rest, no one had the energy for any pointless trouble.

After getting up in the morning, Lin Chuan washed up briefly by the river and saw Terai approaching with two fish in hand. They had seen plenty of fish when they arrived by the river yesterday, but since they had snake meat to eat, they had not gone into the water to catch any.

"Try something fresh—river fish sashimi." Terai tossed one live fish to Lin Chuan, then sliced the other with a kunai and enjoyed the river fish sashimi by the water.

Lin Chuan picked up the fish and smelled its fishy odor, feeling disgusted inside. But his body was honest. He also took out a kunai, sliced up the river fish, and ate a meal of sashimi. Next came the study of a new ninjutsu.

They had to master a B-rank ninjutsu within half a month. That was far more difficult than what those who chose C-rank ninjutsu faced. If he had not been greedy and had chosen a C-rank ninjutsu, learning it would have been much faster. But the chance to choose a B-rank ninjutsu was hard to come by, especially when he could freely pick from such a large collection. How could he possibly pass up the opportunity to learn a new ninjutsu?

To speed up his progress, he created a Shadow Clone to think alongside him. It was equivalent to having two of himself studying at once, making him twice as fast as everyone else.

Seeing this, Terai glanced at him from afar with a grave expression. He had not expected Lin Chuan to know the Shadow Clone technique. Though Terai knew it as well, Lin Chuan was only seven years old. The title of genius truly suited him. Teaming up with him had been Terai's wisest decision. He then collected his thoughts and returned to studying his own new ninjutsu.

Lin Chuan and his Shadow Clone pondered for the entire morning. Once the clone dispersed and its memories returned to the original body, he finally gained some understanding of Heavenly Weeping, this new ninjutsu. He knew how to compress a high-density water needle in his mouth, but the water needle he spat out lacked sufficient power.

As everyone knew, when eating watermelon, the human mouth could also serve as a seed launcher. He needed to give the high-density water needle an extremely fast initial velocity in his mouth for it to possess power and penetration. This technique involved both chakra shape transformation—"water needle"—and chakra nature transformation—"water nature."

A B-rank ninjutsu truly deserved its rank. It involved both shape transformation and nature transformation. This was quite an eye-opener for him. It even felt harder to learn than the Rasengan. Naruto had taken so long only because his chakra control was poor.

To learn this ninjutsu, he still needed to solve two major problems...

First, how could he condense a high-density water needle inside his mouth?

This required precise chakra control. After a long period of training in chakra shape transformation, he had no issue controlling chakra's form. Water was also easy to shape, so condensing a water needle was not difficult for him. At most, the needle would be a little larger.

The difficult part was the water needle's density. If it was not sturdy enough, it would shatter upon impact, let alone pierce a target's body or even penetrate Susanoo.

Second, how could he fire the water needle?

This concerned the water needle's penetration and power. Whether it could pierce through an enemy's heart or eyes depended greatly on speed.

For ninjutsu like Water Shock Wave, which did not rely on speed, there was no need for such powerful impact. Gathering chakra in the throat and spraying it from the mouth provided just enough speed.

But Heavenly Weeping was different. Speed was penetration. To achieve an extremely fast initial velocity, he would have to rely on some physics tricks to make the water needle faster.

The ninjutsu scroll did not explain how to give a high-density water needle muzzle velocity within the limited space of the mouth. It merely said to use chakra to spray it out. Perhaps only the Second Hokage had ever used this technique.

He also knew of another ninja, Genma Shiranui, who could spit senbon—basically toothpicks. But Lin Chuan could not meet him and had no way to learn his senbon-launching technique. Still, firing senbon probably had something to do with chakra.

He had another method to increase the high-density water needle's initial velocity: pressurization or depressurization. The greater the pressure difference, the faster the flow speed. It was similar to the decompression phenomenon in an airplane accident, where a hole could suck people out.

If he could increase the high-density water needle's acceleration, its initial velocity would be even faster. Speed was penetration. As long as the high-density water needle accelerated over a long enough distance, piercing Susanoo would not be a dream.

Unfortunately, the mouth was too small. Even if he made the acceleration passage spiral-shaped, it could not hold many loops. Unless he could extend the water needle's acceleration passage into his esophagus, arranging a straight path from his stomach to his mouth, the needle's penetration might become even stronger. But that would consume much more chakra.

It would be better to increase the water needle's initial velocity. That was easier to learn than increasing its acceleration and would also save chakra.

Initial velocity—he only needed to find a way to improve the starting speed.

Acceleration—he would need to construct a chakra acceleration passage for the water needle from his stomach to his mouth.

Just from the names alone, it was obvious which was more complicated. He would start with the simpler method. He could study the overly complicated acceleration passage later, since he did not currently need to face enemies capable of using Susanoo.

The learning process remained dull and tedious, and he even had to do math problems. What a headache. He had not expected to calculate pressure differences even without going to school. Fortunately, he had not forgotten his physics lessons.

He quickly condensed a water needle as thick as his little finger inside his mouth. With his chakra control, little-finger thickness was already the limit.

He then pressurized his mouth and fired the water needle at a large tree some distance away. With a whoosh, the water needle embedded itself in the trunk. It did not pierce through the tree. Instead, it shattered into pieces, proving that the water needle was not strong enough.

He then tried depressurizing his mouth and fired another water needle at the distant tree. With a whoosh, it embedded itself in the trunk. He jumped over to inspect its penetration and discovered that depressurization was more powerful.

If the ground where he stood was at standard atmospheric pressure, he found depressurization easier. Pressurization had material limits, after all. His mouth could not withstand sustained pressure increases. If he pressurized too much and blew up his mouth, it would be ruined.

He also knew that as altitude increased, the air grew thinner and atmospheric pressure dropped accordingly. In higher-altitude environments, using pressurization to create a greater pressure difference would make the fired water needle more powerful.

In low-altitude environments, using negative pressure to create a greater pressure difference would make the fired water needle more powerful.

No wonder firing water needles with negative pressure was stronger. Konoha was located in the center of the continent, and its elevation was indeed not high. In the future, he could choose suitable pressurization or negative-pressure acceleration based on changes in altitude, making the water needle's initial velocity even faster.

Having clarified the principles behind Heavenly Weeping, he opened the ninjutsu panel...

[Ninjutsu]

[Water Release]

[C-rank Ninjutsu: Water Release · Water Clone (Genin: 156/1000)]

[C-rank Ninjutsu: Water Release · Water Shock Wave (Genin: 145/1000)]

[B-rank Ninjutsu: Water Release · Water Formation Wall (Usable: 19/100) (Two hand seals)]

[B-rank Ninjutsu: Water Release · Water Dragon Bullet (Usable: 20/100) (Six hand seals)]

[B-rank Ninjutsu: Water Release · Heavenly Weeping (Beginner: 2/10)]