Physics Masterstroke

Lin Chuan and Terai said nothing all night. Neither felt like talking, so they slept in the tree. Nothing unusual happened last night. It seemed everyone had been worn down by the instructor's torment. After finally getting a chance to rest, no one had the energy for any messy nonsense.

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

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

Lin Chuan picked up the fish and sniffed its fishy smell. He was disgusted inwardly, but his body was honest. He also pulled out a kunai, sliced up the river fish, and ate a meal of river fish sashimi. Next came learning a new ninjutsu.

They had to learn 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, he would have learned it much faster. But the chance to choose a B-rank ninjutsu was rare, especially when he could pick freely from such a large pile of ninjutsu. How could he possibly miss the opportunity to learn a new technique?

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.

Terai, who saw this, cast a solemn glance from afar. He had not expected Lin Chuan to know the Shadow Clone technique. Although he knew it too, Lin Chuan was only seven years old. The word genius truly suited him. Teaming up with Lin Chuan had been Terai's most correct decision. He then gathered his thoughts and returned to studying his own new ninjutsu.

Lin Chuan and his Shadow Clone pondered for an entire morning. When the Shadow Clone dispersed and its memories returned to his body, he finally gained some insight into Heavenly Weeping, this new ninjutsu. He understood how to compress high-density water needles in his mouth, but the water needles he spat out lacked power.

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

It truly deserved to be called a B-rank ninjutsu. It involved both shape transformation and nature transformation. This had really broadened his horizons. He even felt that learning the Rasengan was not as difficult as this. Naruto had needed so much time because his chakra control was poor.

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

The first was how to condense high-density water needles in his mouth.

This required a ninja to have precise chakra control. After practicing chakra shape transformation for so long, he had no issue with controlling chakra's form. In addition, water was easy to shape. Condensing water needles was not difficult for him; at most, the needles would be a little thicker.

The difficult part was the density of the water needles. If they were not solid enough, they would shatter easily upon impact, let alone pierce a target's body—or even penetrate Susanoo.

The second was how to launch the water needles.

This concerned the water needles' penetration and power. Whether they 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 rapid impact force. Gathering chakra in the throat gave it just enough speed when it was sprayed from the mouth.

But Heavenly Weeping was different. Speed was penetration. It required an extremely fast initial velocity, which meant he had to use some physics mastery to make the water needles faster from the start.

How could he give high-density water needles muzzle velocity within the limited space of his mouth? The ninjutsu scroll did not say. It only stated that chakra should be used to spray them out. Perhaps only the Second Hokage had ever used this ninjutsu.

He also knew of another ninja, Genma Shiranui, who could spit senbon—essentially toothpicks. But he could not meet him, so he could not learn his senbon-launching technique. Still, launching senbon probably had something to do with chakra.

He had another way to increase the initial speed of high-density water needles: increasing or decreasing pressure. The greater the pressure difference, the faster the flow, similar to the decompression phenomenon when a damaged aircraft sucked people out through a hole.

If he could increase the acceleration of the high-density water needles, their initial velocity would become faster. Speed was penetration. As long as the high-density water needles had a sufficiently long acceleration distance, penetrating Susanoo would not be a dream.

Unfortunately, the oral cavity was too small. Even if he made the acceleration channel spiral-shaped, his mouth could not hold many turns. Unless he could place the high-density water needle's acceleration channel in his esophagus, lining it up from his stomach to his mouth, the needles might gain greater penetration. But that would consume much more chakra.

He might as well increase the water needles' initial velocity. That was easier to learn than increasing their acceleration, and it would save chakra.

For initial velocity, he only needed to find a way to increase the starting speed.

For acceleration, he would need to construct a chakra acceleration channel for the water needles from his stomach to his mouth.

Just from their names, it was obvious which one was more complicated. He would start with the simpler one. He could ponder the overly complicated acceleration channel later, since he did not need to face enemies who could use Susanoo right now.

The learning process remained dull and tedious, and he even had to do math problems. It really gave him a headache. He had not expected that even without attending school, he would still have to calculate pressure differences. Fortunately, he had not forgotten his physics lessons.

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

He then pressurized his mouth and fired a water needle at a large tree some distance away. With a whoosh, the water needle struck the trunk. It did not pierce through it; instead, the water needle shattered into pieces, showing that it was not strong enough.

He then tried reducing the pressure in his mouth and fired another water needle at the distant tree. With a whoosh, the water needle embedded itself in the trunk. He jumped over to inspect its penetration and found that reduced pressure produced greater power.

If the ground where he stood was at standard atmospheric pressure, he found that reducing pressure would be easier. After all, pressurization had material limits. His mouth could not withstand sustained pressure increases. If it burst from excessive pressure, his mouth would be ruined.

He also knew that as altitude increased, the air grew thinner and atmospheric pressure decreased accordingly. Thus, at higher altitudes, using pressurization to create a greater pressure difference would make the water needles more powerful.

At lower altitudes, using negative pressure to create a greater pressure difference would make the water needles more powerful.

No wonder firing water needles with negative pressure was more powerful. Konoha was located in the center of the continent, and its altitude was indeed low. In the future, he could choose suitable pressurization or negative-pressure acceleration based on changes in altitude, making the water needles' initial velocity even faster.

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

[Ninjutsu]

[Water Release Ninjutsu]

[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)]