Pros and cons of thermal expansion and cold contraction, thermal expansion and cold contraction and

The deflated table tennis ball, as long as it is not broken, can be scalded with hot water, which is due to the use of the gas in the table tennis ball to expand by heating. The rails on the railway are sections of joints where there are certain gaps, the purpose of which is to prevent thermal expansion and contraction. The store is not full of drinks to prevent the bottles from expanding and shrinking from the heat.

There are some gaps in the rails at intervals, for fear that the rails will be crowded in the summer.

Freshly boiled eggs are immediately rinsed in cold water and peeled, because the hot eggs are suddenly cold and shrink in size.

Thermal expansion and contraction are factors that must be considered in engineering, and it often causes us trouble. For example, rails expand when heated, the temperature rises by 1, and the 1 km long track elongates by 1 centimeter, which seems to change very little. However, if the temperature difference between summer and winter is 55, taking Tianjin to Beijing as an example, the track is 120 kilometers long, and the summer is 66 meters longer than the winter.

That's a big number. If the rails are tightly connected when laid, the 66 meters will destroy the entire route, so when laying the rails, there must be a certain gap in the connected places.

People also often take advantage of the thermal expansion and contraction of objects in their daily lives. For example, if you soak a hard-boiled egg in cold water, the egg will peel easily, as a result of the different shrinkage of the shell and the egg white. Soak the unscrewed metal cap in hot water for a while, and the cap will be easily unscrewed.

Disadvantages of thermal expansion and cold contraction:

1.Wires that are installed too tightly in winter will break

2.Thermal expansion and contraction will make the accuracy of the measuring instrument worse, people are trying to find materials with a small coefficient of thermal expansion to make measuring tools, and the precision measurement requires constant temperature, which has the same impact on high-precision equipment, so that many equipment can not be as accurate as imagined in the design.

3. Cause the water pipe to burst, plus the water pipe will freeze and crack the pipe if it freezes in winter.

4 Know about the 1986 U.S. Space Shuttle Challenger accident? It is caused by the thermal expansion and contraction of the rubber sealing ring.

The advantages of thermal expansion and cold contraction:

Liquid thermometer

1. Put wheels on the train

2. Use hot water to round the deflated table tennis ball.

3. Thermal expansion and cold contraction, after steam washing, washing the face with cold and hot water alternately, can make the face ** in the process of alternating hot and cold to be exercised and elastic.

Everything always has two sides, and the same is true for the thermal expansion and contraction of objects. We need to prevent its negative side and use its positive side to serve humanity.

In different situations, there are different pros and cons!

What are you talking about?

Categories: Education, Science, >> Learning Aid.

Problem description:1When the temperature of an object (a normal substance, i.e., thermal expansion and contraction) increases, does its internal energy increase? If yes, is it because of overcoming the gravitational pull of the molecule to do the work?

2.When another object (let's say water at 0 4 degrees, cold expansion and heat contraction) starts from zero degrees, the temperature rises, but does not exceed 4 degrees. Is the internal energy increasing at this time? And if so, did you do the work at that time because of overcoming molecular repulsion?

It would be nice to have a detailed explanation, thank you.

Analysis: As the temperature increases, the thermal motion of the molecule accelerates, and the kinetic energy of the molecule increases.

Similarly, a body with thermal expansion and contraction increases in temperature and becomes larger in volume, but the force between molecules does not necessarily manifest as gravitational force, in the same way, an object in which the temperature of an object expands and shrinks becomes smaller, but the force between molecules does not necessarily manifest as repulsion, so your explanation is incorrect. There is no necessary relationship between the forces between molecules and the change in volume, and cannot be used to judge the change in internal energy.

There are two variables in these two mentions, the temperature and volume have changed, which is difficult to judge. But the internal energy should all increase.

The phenomenon of heat expansion and cold contraction can be seen everywhere in life, and many people usually use this principle to solve various problems in life.

The phenomenon and explanation of heat expansion and cold contraction in life:

1. In winter, the water pipe is broken, because the temperature key width is relatively low in winter, and the water pipe will shrink.

2 Sometimes the road surface will arch upwards in summer, which is caused by the expansion of the road surface, so there are gaps left in the road surface every other distance, and the temperature increase will make the road surface arch, using the principle of heat expansion.

Prudence 3 bought cans are difficult to open, because the factory production is put into the heat, gas expansion, after cooling, the volume of gas inside decreases, the outside atmospheric pressure is greater than the inside, so it is difficult to open, you can heat the can a little to open it is easy to open, it is also the use of the principle of heat rise, the internal temperature rises, the gas expands, and then you can open the can lid.

4. The inside of the thermometer is mercury and other liquids, and the rise and fall of the temperature width and brightness will make the thermometer float up and down, using the principle of thermal expansion and cold contraction.

There are many phenomena of heat expansion and cold contraction, which can be seen everywhere in life, and many problems can be solved by using the principle of heat expansion and cold contraction.

When it is hot, the railroad tracks and asphalt roads are also long, which is a superficial phenomenon, and the fundamental reason is because of "heat rise and cold contraction".

Since the motion of particles (atoms) in an object changes with temperature, when the temperature rises, the vibration amplitude of the particles increases, causing the object to expand; However, when the temperature drops, the vibration amplitude of the particles decreases, causing the object to shrink.

Substances such as water (below 4°C), antimony, bismuth, gallium, and bronze shrink when heated in certain temperature ranges and expand when cold, which is the opposite of the characteristics of ordinary objects.

Thermal expansion and cold contraction. Thermal expansion and contraction refers to the characteristic that an object expands when it is not hot and shrinks when it is cold. Since the motion of particles (atoms) in an object changes with temperature, when the temperature rises, the vibration amplitude of the particles increases, causing the object to expand;

However, when the temperature drops, the vibration amplitude of the particles decreases, causing the object to shrink.

Introduction to thermal expansion and cold contraction:

Thermal expansion and contraction are the characteristics of general objects, but substances such as water, below 4 degrees Celsius, antimony, bismuth, gallium, and bronze contract when heated in certain temperature ranges, and expand when cold, which is the opposite of the characteristics of general objects.

Applications of thermal expansion and contraction:

1. After the egg is cooked, if it is cooled in cold water, the egg shell and the egg white are not easy to stick, because the degree of cold and hot contraction of the egg shell and egg white is not the same, so there is a gap, which is easier to peel.

2. The cans that are bought back often have to use a lot of force to open, because when the cans are sealed, the hot air enters the inside, when the temperature drops, the volume shrinks, and the outside atmospheric pressure is stronger than the pressure of the gas inside the can, so it is not easy to open the cap, if we heat the cans a little, it can be easily opened.

3. When building roads, in order to avoid road festering caused by the expansion and compression of high-temperature roads in summer and the contraction and stretching of low-temperature roads in winter, a gap is left every other distance, so as to reduce the concentration of excessive strength, prolong the service life of the road, and ensure everyone's travel safety. <>

1. The phenomenon and explanation of thermal expansion and cold contraction

Thermal expansion and contraction refers to the property that an object expands when it is heated and shrinks when it is cold.

Since the motion of particles (atoms) in an object changes with temperature, when the temperature rises, the vibration amplitude of the particle imitation detector increases, causing the object to expand. However, when the temperature drops, the vibration amplitude of the particles decreases, causing the object to shrink.

Second, the phenomenon and explanation of thermal expansion and contraction in life

1. The water pipe is ruptured in winter, because the temperature is lower in winter, and the water pipe will shrink.

2 Sometimes the road surface will arch upwards in summer, which is caused by the expansion of the road surface, so there are gaps left in the road surface every other distance, and the temperature increase will make the road surface arch, using the principle of heat expansion.

3. The canned food I bought is very leaky and difficult to open, because the factory is hot when it is put in, the gas expands, the volume of gas inside decreases after cooling, and the atmospheric pressure outside is greater than the inside, so it is difficult to open, and the can can be easily opened by heating it slightly, and it is also the use of the principle of heat expansion, the internal temperature rises, the gas expands, and then you can open the canned cover.

4. The inside of the thermometer is mercury and other liquids, and the temperature rise and fall will make the thermometer float up and down, using the principle of heat expansion and cold contraction.