"The imperial capital is really cold enough. Feng Hao walked into the school snack city, found his daughter's location, and then ordered the food, waiting for it to be fried.

"Dad, the coldness of the imperial capital is different from the coldness of Guangyue. Feng Yuechan tilted her head and said playfully.

"What's the difference?" Feng Hao asked.

"The cold in the north is a physical attack, and the cold in the south is a magical attack. Feng Yuechan laughed, "Actually, it's because your way of dressing is unscientific." ”

"How do you say this?" Feng Hao glanced at the way the students around him were dressed, and said puzzledly, "Everyone is a set of autumn clothes and pants inside, and a set of coats on the outside. If it's still too cold, add a sweater in the middle. ”

"Just because everyone is dressed like this doesn't mean it's a scientific way of dressing. Feng Yuechan said seriously, "In ancient Western times, before Copernicus's heliocentrism, everyone believed in geocentrism. In ancient China, we have always believed that the world view of the sky is round and the chicken eggs are round. ”

"Uh......" Feng Hao was stunned.

"Why? Don't believe it? I'll prove it to you. Feng Yuechan was eager to try.

"This ...... Can you prove it?" Feng Hao said strangely.

"Yes, it can be proven. Mathematical modeling is the use of mathematics to solve real-world problems. Feng Yuechan said seriously, "Recently, I have been preparing for the digital simulation competition of the United States imperialism, so I have studied digital modeling. According to the problem-solving method of digital model, you need to ask questions, choose methods, derive formulas, solve models, and answer questions. ”

"But the words 'the scientific way of dressing' can't be linked to mathematics at all. Feng Hao frowned.

"Who said you can't?" Feng Yuechan reminded, "The topic has to be read through several times, if you don't understand, read the topic, if you don't understand, continue to read the topic." Come read it with me. ”

"The scientific way to get dressed. ”

"The scientific way to get dressed. ”

"The scientific way to get dressed. ”

“……”

"Got it?"

"I ......"

(?_?)

Feng Hao said that there was no way to connect at all.

Ay.

Feng Yuechan sighed: "I can't understand the question, that's because you didn't think in the direction of mathematics." Come, let me show you how to solve the problem. ”

"First of all, let's say that man is a bucket. That is, a cylinder with a constant temperature of 37 degrees, a base radius of 20 centimeters, and a height of 175 centimeters. ”

"Then let's assume again. Clothes can be seen as several layers of buckets wrapped around the outer layer of this bucket. ”

"Now, our question is, if you were given an autumn coat and a trench coat, which bucket would you wear on the outermost?"

Feng Yuechan stopped, looked at her father with a "oh oh", took out a pen and paper with a sense of accomplishment, drew a three-dimensional coordinate axis, and said.

"The bucket inside is you who are not wearing clothes, and you who are wearing autumn clothes are wearing a bucket outside of you, and you who are wearing autumn clothes and a coat when you put a bucket on the outside. ”

"Understood. ”

Feng Hao suddenly realized.

Although it is not a profound thing, and it ignores the differences in height, stature, and sensibility of different people, the way of thinking that can materialize abstract concepts into mathematical models is exquisite in itself.

Feng Yuechan continued: "The question is raised, so let's use experiments and theories to explore which clothes should be worn outside. ”

"First of all, we intuitively feel the warmth effect of different clothes. The core that determines the warmth of a garment is its thermal conductivity and thickness. ”

"We wrapped our clothes in a warm water bag with an initial temperature of about 54 degrees Celsius and measured how much the temperature of the clothes had risen after five minutes. ”

Five minutes later.

"In the same amount of time, the autumn coat rose to 44 degrees, almost close to the hot water bottle temperature, while the trench coat only rose by 10 degrees. It shows that the warmth effect of a windbreaker is far better than that of an autumn coat. The next question is whether you should wear it on the outside or inside. ”

"Here, we need to use the radial heat flow equation of the barrel wall below the ordinate to interpret the ......"

φ=（T0-T∞）/{[ln(R2/R1)]/2πLK1 [ln(R3/R2)]/2πLK2}

"The main component of autumn clothes and pants is cotton, and the thermal conductivity K1 = 0050W/mK. The main components of the trench coat are wool and polyester fibers, and the thermal conductivity K2 = 0029W/mK, and then the thickness of the clothes is measured and brought into the formula. ”

"If the jersey is worn inside and the windbreaker is worn outside, the radius of the person R1 is 200mm, R2 is the radius of the person plus the thickness of the autumn coat, which is 20342mm, and R3 is the person plus the thickness of the autumn coat plus the thickness of the coat, which is 20875mm, and the heat dissipation can be found to be 3305W by substituting the formula. ”

"In the same way, if the jersey is worn on the outside and the windbreaker is worn on the inside, the heat dissipation will be 3288W. ”

"See?" (⊙.)

o ⊙) Ah!

What to see?

Feng Hao looked confused.

I don't know what to see.

Feng Yuechan shook her head: "If you wear the coat inside the jersey, your heat dissipation power drops by a full two watts, what does it mean, do you understand?"

(⊙ o ⊙) Ah!

Don't understand.

Feng Hao's face was confused.

I don't know what to understand.

Feng Yuechan sighed: "If you wear your autumn clothes outside and stand outside for two whole days, you can save a whole egg of calories." ”

(⊙ o ⊙) Ah!

This mathematical thinking, my father said that he couldn't keep up.

"Forget it, I'll show you the temperature distribution map in both cases, and it's clear at a glance. ”

As soon as the words fell, two holograms appeared in front of me.

Diagram of the temperature distribution of the windbreaker in the autumn coat (author's note: it cannot be shown, it can only be dictated, the temperature of the readers of the cylinder is represented by red, the red spreads outward, and gradually becomes the yellow with low temperature, but the whole red covers the thickness of the jersey and spreads to the surface of the windbreaker. It then fades into a cooler blue in a trench coat. ）

Temperature distribution map of the autumn coat outside and the windbreaker inside (author's note: it cannot be displayed, it can only be dictated, representing the hottest red color that is bound to the contact surface of the windbreaker and the readers)

"Through the temperature chart, you will find that wearing an autumn coat on the outside and a windbreaker on the inside will firmly bind the temperature around your body, so this is a more scientific way to wear it. ”

"So, if you are afraid of the cold when you go out in the future, wear autumn clothes to keep warm scientifically!"

○|￣|_

"This is really a choice between demeanor and temperature and temperature and temperament, a problem in life. Feng Hao smiled bitterly, "I finally understand a problem that has been bothering me for a long time. ”

"What's the problem?" Feng Yuechan said curiously.

"Why does Superman wear underwear. Feng Hao said with a serious face.

Poof—

(*^__^*) hee hee ......

Feng Yuechan leaned forward and leaned back with a smile, and when she saw her father eating deflated, she felt inexplicably happy, and suddenly thought of something, and asked: "Dad, I haven't been back for a month, is it okay for the panda to take care of it?"

"Don't worry, Panda is fine. Feng Hao said casually, "I have found a breeder for it, who is very professional and ensures that it can enjoy unique care." ”