Physical Phenomena in Life and Their Applications 80

In the seemingly ordinary phenomena in life, there are actually a lot of simple physics knowledge hidden. Physics is all around us, as long as you observe and experience carefully, you will find that you have come to the colorful world of physics, where you will find a new starting point in life. For example, five-spice tea eggs are loved by people, especially when eaten hot.

Careful people will find that when the eggs are just taken out of the boiling marinade, if you are in a hurry to peel the shell and eat the eggs, it is inevitable that the shell and "meat" will be peeled off together. To solve this problem, there is a trick, which is to soak the freshly cooked eggs in cold water for a while, and then peel them, so that the eggshells are easy to peel off. This is the use of the thermal expansion and contraction of matter.

When different substances are heated or cooled, the speed and amplitude of expansion and contraction vary. Generally speaking, substances with low density are more likely to expand and contract than substances with high density, and substances with fast heat transfer are more likely to expand and contract than substances with slow heat transfer. Eggs are made up of a hard shell and a soft egg white and yolk, and their expansion and contraction are not the same.

In the case of little change in temperature, or relatively slow and uniform change, nothing is visible; Once the temperature changes drastically, the eggshell and egg whites stretch at an inconsistent pace. The boiled egg is immediately immersed in cold water, the temperature of the eggshell decreases, and it shrinks quickly, while the egg white is still the original temperature and has not yet shrunk, at this time, a small part of the egg white is pressed by the eggshell to the empty end of the egg. Then the egg white gradually shrinks as the temperature decreases, and the eggshell shrinks very slowly, so that the egg white is separated from the eggshell, so that the peel does not come down with the "meat" of the shell.

Understanding this truth is very useful to us. For example, in the design of houses and bridges, reinforced concrete is widely used, because the expansion degree of steel and concrete is almost exactly the same, and it is not affected by temperature, although the temperature of spring, summer, autumn and winter is different, it will not produce harmful forces, so the houses and bridges caused by it are very strong. In the colorful world, there are colorful physical phenomena, as long as we carefully observe the things around us and find their laws, we can use them.

Examples of physical phenomena in life are as follows:1. Rice cooker cooking, electric wok cooking, and electric kettle boiling water convert electrical energy into internal energy.

2. Exhaust fan.

Range hood) converts electrical energy into mechanical energy.

Air conversion using air convection.

3. The three-pin plug of the rice cooker, electric wok, and electric kettle should be inserted into the three-hole socket to prevent the occurrence of electrical leakage and electric shock accidents.

4. The microwave oven heats evenly, with high thermal efficiency, hygienic and pollution-free. The heating principle is to use electrical energy to convert electromagnetic energy, and then convert electromagnetic energy into internal energy.

5. The electric lamp in the kitchen uses the thermal effect of electric current to work and convert electrical energy into internal energy and light energy.

6. Kitchen stove (honeycomb coal.

stoves, liquefied gas stoves, coal stoves, wood stoves) is the chemical energy.

Converted into internal energy, i.e. the heat emitted by fuel combustion.