Chapter 52: Specific Surface Area

Because Wei Dalei wasn't accompanying them this time, Chen Mu made more preparations than usual before departure.

Around 7:30, everyone got up one after another.

There was no washing up; water remained a precious resource, usable only for drinking, so everyone looked dirty.

In fact, fetching some non‑drinking water outside isn't too hard; in April, Shangshi already has a large day‑night temperature difference, and in the morning you can often see crystal‑clear dew droplets on the roadside grass.

Although the amount is small and can't compare to autumn, for people now a single drop of dew can meet many people's daily water needs.

However, places with grass patches are relatively dangerous; Chen Mu had also observed that in some lush spots the grass grows taller than the road, and later they could consider going there to collect dew.

But this isn't currently the most urgent matter.

After all, the apocalypse has only been around for about a week; many things are far more important than washing up, and tasks need to be done one by one.

……

Du Jia Jia has grown accustomed to her role as the dedicated cook; after getting up and tidying herself a bit, she starts thinking about breakfast, and because Chen Mu and the others are heading out again, she also needs to prepare early.

"Should we bring something to eat on the road?" Chef Du had already stepped into her role, taking responsibility for everyone's meals.

"No need, this time we won't spend too much time."

"Don't we need to bring something for the new members? They might have been hungry for a long time."

"When I left, they still had some food left; holding out until now should be fine," He Ying explained.

Chen Mu also said, "Besides, carrying cooked food might attract flies and such, only adding trouble."

"All right." Du Jia Jia nodded, feeling a bit disappointed.

……

After everyone finished breakfast, the time was exactly eight o'clock.

Chen Mu readied his weapon, led He Ying and Sun Yuan, and set out again.

Although they'd walked that route several times before, each trip still felt heavy‑hearted, especially now that they knew about the brutal fighting outside among humans, giving them an increasingly ominous premonition.

Chen Mu sometimes just wants to hide and do nothing, which might let him live longer, but his nature has always made him prefer to draw his sword and settle things quickly rather than wait for a slow death.

……

"You say this thing is really a hand grenade?"

He Ying walked while holding the two stone chunks Chen Mu had given her before departure; although she found it hard to believe that something as ordinary as a rock could be an explosive grenade, she still handled it with great care.

"Mm, as long as there's no violent impact, it'll be fine."

Regarding the hand grenades made by Dong Junwei, everyone had studied them before, but the detonation mechanism remains unclear; it has no fuse or similar part, and seems to explode only upon impact.

But just how violent an impact must be to reach the threshold is unknown—without equipment we can't measure it, only have a rough feel; fortunately the device is fairly stable, so ordinary shaking and bumps won't accidentally set it off.

The grenade's power is proportional to Dong Junwei's current ability; the more carefully she makes it, the longer she spends, the more spiritual energy she puts in, the greater the power.

Tang Jing had also wondered whether the grenade's power would diminish after long storage.

But judging by the past few days, there's no such problem.

This is different from metal.

The metal objects Dong Junwei heats, although their heat‑dissipation speed is far below normal and their heat capacity seems to have changed greatly, still eventually cool down slowly.

Tang Jing once conducted an experiment: a heated iron block that was smoking needed a full twenty‑four hours to cool completely to room temperature, and the cooling process was linear.

It's still unclear whether, after Dong Junwei's ability strengthens, her heat‑retention time improves; after all, the squad leader's awakening hasn't been long enough, and her abilities are limited, so she can't run more detailed experiments.

At departure, Chen Mu carried four grenades himself, gave two to He Ying, and one to Sun Yuan.

Moreover, he made a small shield for Sun Yuan; originally he'd planned to give him a spear, but this first‑year junior seemed terrified of fighting, trembling even holding a spear with no opponent, so in the end he gave him a thin iron shield for self‑defense in emergencies.

Sun Yuan carried the shield at his side and felt it novel all the way, even speaking far less.

Only now did He Ying understand what Tang Jing meant yesterday by "no need for close combat"; if this device really has the power Chen Mu described, there's indeed little need to engage in hand‑to‑hand fighting.

Too bad everyone is wearing summer clothing.

Take Chen Mu as an example: his short‑sleeve T‑shirt has no pockets, and while his shorts have two small side pockets, they're too tiny to carry much.

Chen Mu had also considered modifying his clothes to add a few pockets, but in practice it's nearly impossible; every time he tries to use his ability on fabrics like towels, it fails.

It's not that his ability doesn't work on cloth; rather, each attempt ends in a mess—the fabric seems to refuse to obey his will, and the spiritual energy drained is several times that for other objects.

In theory, fabric's low density shouldn't cause this, but in fact it does.

He and Tang Jing had also discussed this issue.

In the end they could only guess at a rough possibility.

Because unlike dense materials such as metal and plastic, fabric is not strictly a single entity.

Take a piece of cotton cloth as an example: it's made of countless cotton threads, each thread itself composed of countless cotton fibers; thus, although it looks like Chen Mu is applying his ability to a piece of fabric, in reality his target is innumerable fibers, and the difficulty is easy to imagine.

Here's a more understandable example.

Chen Mu can easily control a copper block, but the same mass of copper wire presents an exponentially greater difficulty.

Therefore, for Chen Mu's ability, besides an object's density, Tang Jing has introduced a new key attribute.

Specific surface area.

Specific surface area refers to the total surface area possessed by a unit mass of an object.

Another more intuitive, easier‑to‑understand definition is the ratio of an object's area to its volume.

Obviously, a spherical object has the smallest specific surface area, and roughly speaking, the more irregular the shape of a single solid body, the larger its specific surface area tends to be.

But the best way to increase specific surface area is to cut the object.

For the same mass of iron, a solid iron ball and a pile of iron powder have theoretically the same volume, but their specific surface areas differ enormously.

Obviously.

Fabric falls into this category.