2. Why does water splash when poured into boiling oil? Answer: Because the density of water is greater than that of oil, water will be on oil when it enters oil, and the temperature of oil is much higher than the boiling point of water, so water will boil and splash when heated.
3. Why does sugar melt faster in hot water than in cold water? A: According to the molecular dynamics theory, the higher the temperature, the faster the irregular movement of molecules, so the faster the water molecules and sugar molecules in hot water move, the faster they merge with each other and the faster they melt.
4. Why should salt be sprinkled on the road after the heavy snow in winter? A: Sprinkling salt reduces the melting point of snow, which can melt snow at a lower temperature and restore traffic as soon as possible.
5. Why is there no signal when the mobile phone is placed in the iron box? Answer: Because the iron box is made of iron, the iron box will have shielding effect under the magnetic field, so the mobile phone can't receive the network signal.
6. What does it mean to sit on the floor and travel 80,000 miles a day? Answer: Because the earth rotates, the earth rotates once a day. Even if people don't move, one day people will move relative to space.
7. Why is the sky blue? A: Because various substances in the air absorb more red, orange and green light, a large part of blue light is refracted or reflected to our eyes, so the sky we see is blue.
8. Why are the two rails at the turn of the railway not generally high, but have a certain inclination, which is stipulated by the national standard? Answer: Because this can improve the speed of the train, the inclination angle makes the centripetal force provided by gravity and rail pressure components to the train greater than that provided by rail pressure alone, which can meet the centripetal force required for a higher speed of the train; The maximum pressure of the orbit is fixed, and the inclination angle will affect the gravity to provide a part of the centripetal force, which will affect the centripetal force and thus determine the speed. Therefore, the maximum speed of the train is determined by the inclination angle stipulated by the state.
9. Why do astronauts have a brief coma when they return to Earth from space? A: Frankly speaking, because of the influence of overweight and weightlessness, too much or too little blood flows into the brain, which makes people dizzy.
10. What is the most basic power principle of a jet plane? A: By using the principle of conservation of momentum, the high-temperature gas ejected by the aircraft is opposite to the direction of the aircraft, that is, the formula: 0 = (m-m) v-mv', where m is the weight of the original aircraft, m is the weight of the ejected gas, v is the speed after the aircraft ejects the gas, and v' is the speed of the ejected gas.