The accumulation of common sense | Scientific common sense in life

1. Common sense of physics in everyday life

Stethoscope: The human body produces sounds from certain organs. With a disease of heart, lungs, trachea, stomach, etc., sounds of organs change according to certain characteristics. Doctors can listen to them through a stethoscope, go out and diagnose disease accordingly.

Rearview mirror. The rear view mirror outside cab of car is a convex mirror. Using diverging effect of convex mirror on light and characteristics of straight, reduced and virtual imaging, real visible object becomes smaller and viewing distance is longer to ensure driving safety.

Clothes Hook: When plastic clothes hook is close to wall, air between plastic suction cup and wall is squeezed out, and atmospheric pressure presses plastic suction cup firmly against wall. wall. After hanging clothes or school bags, friction generated by plastic suction cup and wall can balance gravity of clothes or school bags, so clothes or school bags can be hung up.

Choose porcelain: tap porcelain with your hand or other object and you can judge quality of porcelain by sound. Since timbre of cracked bowls and basins is much worse than that of ordinary porcelain, bad bowls and basins can be distinguished by their timbre, which is determined by tone.

Disaster monitoring. By tracking infrasonic waves, we can get information about earthquakes and typhoons. Since infrasound is sound below 20 Hz, humans cannot hear it. Some natural disasters, such as earthquakes, volcanic eruptions, typhoons, etc., are accompanied by generation of infrasonic waves, and information about some natural disasters can be obtained by monitoring transmitted infrasonic waves.

Car front windows. With exception of large passenger cars, front windows of most vehicles are tilted. When front glass of car is tilted, passengers in car are reflected in glass and appear to be in front of car, while pedestrians on road cannot appear in air overhead, so image of passengers in car is separated from pedestrians on road. When it is open, driver will not have illusions and avoid accidents caused by plane's mirror display.

2. Common sense of chemistry in everyday life

Food Preservation: To prevent food from becoming damp, spoiled, or deformed, food bags are often filled with carbon dioxide or nitrogen, or a desiccant is placed in bags. Quicklime and calcium chloride mainly absorb water. Iron mainly absorbs oxygen and water, or takes vacuum packing.

The sky is clear after rain: After a thunderstorm in summer, people will feel that airespecially fresh because during lightning a chemical change occurs and some of oxygen in air becomes ozone. Concentrated ozone is very smelly, strong oxidizing ability, can bleach and sterilize. Fine ozone will give people a feeling of freshness. After a thunderstorm, there will be a small amount of ozone in air, so people will feel that air is fresh.

Old wine is more fragrant. The main component of liquor is ethanol. If you bury wine in ground and store it well, after a few years ethanol will react chemically with acetic acid. , which is a relatively small component in liqueur, forming fruity-flavoured ethyl acetate. Although above reaction is a reversible reaction, reaction rate is relatively slow, but longer time, more ethyl acetate will be formed, so wine will be more aromatic as it ages.

Sulfur dioxide in food: Sulfur dioxide is a very important element of inorganic chemical preservatives, it is widely used in food products, for example, for sulfur fumigation in production of dried and canned fruits. used as a prolonged sulfur dioxide agent for fresh storage and storage of grapes and other fruits. Sulfur dioxide can exhibit various technical effects in foods and is commonly referred to as a bleaching agent because sulfur dioxide can react with colored substances to whiten food. On other hand, sulfur dioxide has a reducing effect, which can inhibit oxidase activity, thereby inhibiting enzymatic browning. After extensive toxicological studies, it is believed that: sulfite preparations do not cause obvious harm to most people at current dosage. Another point to be clarified is that sulfites in food must reach a certain dose before they can cause an allergy. Even those who are very sensitive to sulfite allergies are not allergic to all foods processed with sulfites. from this point of view, sulfur dioxide is a relatively safe preservative.

3. Medical common sense in everyday life

Drug Allergy: Patients should first drink more warm water in order to facilitate drug elimination as quickly as possible, while at same time paying attention to changes in body. If severe allergic symptoms occur, appropriate first aid measures can be taken, such as antihistamines, vasoconstrictors, or corticosteroid injections.

Medication times. Medications that should be taken before meals usually do not stimulate stomach much. Drugs that cause obvious irritation of gastrointestinal tract are best taken after meals. Certain drugs such as gastric enzyme tablets, amylase, dilute hydrochloric acid, etc.r., must be taken with food in order to exert its digestive effect in a timely manner and to greatest extent, therefore these drugs should be taken with food. . In order for drug to enter intestines faster and maintain a high concentration, some drugs should be taken in morning on an empty stomach.

Medical alcohol and industrial alcohol:Medical alcohol refers only to 75% ethanol, and content of other substances must not exceed specified standard. Technical alcohol contains a small amount of methanol, which can be absorbed through mucosa of gastrointestinal tract or directly through skin. After methanol enters human body, it enters liver through bloodstream and is converted to formaldehyde, which is ten times more toxic than methanol, by dehydrogenation of liver alcohol dehydrogenase. Formaldehyde is then dehydrogenated to formic acid, which can cause systemic acidosis, which in turn aggravates symptoms of poisoning and harms body.

What medicine does doctor use to get rid of pain of athletes quickly: When watching a football match, you can sometimes see football players who are struggling on a green field, suddenly fall. due to injury, and sometimes rolled over in pain, hugging his thigh. In order for him to continue fighting, doctor ran up, took a small watering can, sprayed medicine on injured part, and then rubbed it and massaged it with cotton wool. After a while, injured athlete got up again and entered competition again. It turned out that watering can was filled with ethyl chloride, a colorless, highly volatile liquid (boiling point 13.1°C). When sprayed on affected area, it instantly evaporates. When volatilized, it absorbs heat, so that temperature of surface of skin drops sharply, and sensations are dulled, thus playing role of analgesia and local anesthesia.

1 Why does sorbet smoke?

Sorbet smokes because there is a lot of invisible water vapor in outside air. When it encounters a very cold sherbet, it turns into mist and surrounds sherbet when it is cold. It seems that sorbet "gassing" "The same.

2 Why do sunflowers always face sun?

Sunflower stems contain a wonderful auxin that is very sensitive to light. When exposed to light, it moves to backlight side, and at same time stimulates cells on backlight side to multiply rapidly, so backlight side grows faster than light side, causing sunflower to produce phototropic bending.

Why do 3 cicadas shed their skin?

The shell (exoskeleton) of cicada is hard and cannot expand as cicada grows. When cicada grows to a certain stage, cicada's exoskeleton restricts cicada's growth, and cicada removes original exoskeleton, this is cicada's swamp.

How do 4 bees make honey?

The bees first spit sweet juice from plucked flowers into empty hive. At night, they suck sweet juice into their honey stomach to cook it, then spit it out and swallow it again. 100 to 240 times finally into sweet honey.

5 mysterious "9"

When a quartz clock hanging on wall stops moving due to a low battery, its second hand will often stop at 9 position on dial. This is due to fact that second hand slows down gravitational moment most at position "9".

6 resonance

Sometimes water pipe makes a crackling sound when water flows out of a nearby faucet. This is due to resonance of pipes as water rushes out of faucet.

7 fuzzy photos

When shooting in front of a TV screen, turn off camera's flash and turn off interior lighting so that pictures taken are clearer. Because reflected light from flash and light on TV screen will interfere with transmitted light of TV screen.

8 air and water

Frozen meat thaws faster in water than in air at same temperature. A hot iron nail cools faster in water than in air of same temperature. A mug of boiling water cools faster when immersed in water than in air of same temperature. All these phenomena indicate that heat transfer properties of water are better than those of air.

9 drops of water at bottom of pot

When pot is filled with cold water, water droplets attached to outer surface of bottom of pot can only dry out after being in flame for a long time, and they won't boil until they dry. conductivity, temperature is about same, until water in pan boils, drops of water will not boil, and drops of water will evaporate on flame and gradually burn to dryness.

10 shapeless mirrors

The farther a person is from mirror, more out of shape they will be, because image in mirror is formed by reflecting a silver plated surface behind mirror, an uneven silver plated surface or uneven glass thickness will cause aliasing. For a non-standard mirror, farther a person is from mirror, greater deviation from normal position of reflected light on silver-plated surface, due to principle of light amplification, and greater deviation from normal position. -The shape of mirror will be.