How does solids expand

Molecules within gases are further apart and weakly attracted to each other. Heat causes the molecules to move faster, heat energy is converted to kinetic energy which means that the volume of a gas increases more than the volume of a solid or liquid.

However, gases that are contained in a fixed volume cannot expand - and so increases in temperature result in increases in pressure. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Why solids expand on heating Ask Question. Asked 5 years, 2 months ago. Active 9 months ago. Viewed 4k times. My attempt: I did not make a huge deal out of the question, and simply thought that it is due to the increase in frequency of vibrations, which now causes greater oscillations about the lattice points, which in turn increases the average volume occupied by atoms, leading to expansion.

Improve this question. Community Bot 1. Lelouch Lelouch 3, 13 13 silver badges 30 30 bronze badges. The usual explanation in school physics is b : When a material gets hot it expands - this is because the molecules in it are moving about more vigorously and so need more room.

There is an explanation here including discussion of the failure of the spring model. Add a comment. Active Oldest Votes. Rakesh Kapoor from University of Alabama at Birmingham Giving the balls more energy increasing the temperature of the atoms will increase the amplitude of the spring's oscillations, which increases the amount of space the atoms will take up. See Figure. Perhaps the most striking effect of this phenomenon is the freezing of water in a pond.

When water near the surface cools down to it is denser than the remaining water and thus will sink to the bottom. Eventually the pond has a uniform temperature of. If the temperature in the surface layer drops below , the water is less dense than the water below, and thus stays near the top. As a result, the pond surface can completely freeze over. Fish and other aquatic life can survive in water beneath ice, due to this unusual characteristic of water. It also produces circulation of water in the pond that is necessary for a healthy ecosystem of the body of water.

Making Connections: Real-World Connections—Filling the Tank Differences in the thermal expansion of materials can lead to interesting effects at the gas station.

One example is the dripping of gasoline from a freshly filled tank on a hot day. Gasoline starts out at the temperature of the ground under the gas station, which is cooler than the air temperature above. The gasoline cools the steel tank when it is filled. Both gasoline and steel tank expand as they warm to air temperature, but gasoline expands much more than steel, and so it may overflow. This difference in expansion can also cause problems when interpreting the gasoline gauge.

Calculating Thermal Expansion: Gas vs. Gas Tank Suppose your How much gasoline has spilled by the time they warm to? The tank and gasoline increase in volume, but the gasoline increases more, so the amount spilled is the difference in their volume changes. The gasoline tank can be treated as solid steel. We can use the equation for volume expansion to calculate the change in volume of the gasoline and of the tank.

Use the equation for volume expansion to calculate the increase in volume of the steel tank:. Alternatively, we can combine these three equations into a single equation. Note that the original volumes are equal. This amount is significant, particularly for a The effect is so striking because the gasoline and steel expand quickly. The rate of change in thermal properties is discussed in Heat and Heat Transfer Methods.

If you try to cap the tank tightly to prevent overflow, you will find that it leaks anyway, either around the cap or by bursting the tank. Tightly constricting the expanding gas is equivalent to compressing it, and both liquids and solids resist being compressed with extremely large forces.

To avoid rupturing rigid containers, these containers have air gaps, which allow them to expand and contract without stressing them. Thermal stress is created by thermal expansion or contraction see Elasticity: Stress and Strain for a discussion of stress and strain. Thermal stress can be destructive, such as when expanding gasoline ruptures a tank. It can also be useful, for example, when two parts are joined together by heating one in manufacturing, then slipping it over the other and allowing the combination to cool.

Thermal stress can explain many phenomena, such as the weathering of rocks and pavement by the expansion of ice when it freezes. What pressure would be created in the gasoline tank considered in Figure , if the gasoline increases in temperature from to without being allowed to expand?

Assume that the bulk modulus for gasoline is. For more on bulk modulus, see Elasticity: Stress and Strain. To solve this problem, we must use the following equation, which relates a change in volume to pressure:. We will use the amount spilled in Figure as the change in volume,. Insert the known values. The bulk modulus for gasoline is.

In the previous example, the change in volume is the amount that would spill. Here, is the original volume of the gasoline. Substituting these values into the equation, we obtain. This pressure is about , much more than a gasoline tank can handle. Forces and pressures created by thermal stress are typically as great as that in the example above.

Railroad tracks and roadways can buckle on hot days if they lack sufficient expansion joints. Power lines sag more in the summer than in the winter, and will snap in cold weather if there is insufficient slack. Cracks open and close in plaster walls as a house warms and cools. Glass cooking pans will crack if cooled rapidly or unevenly, because of differential contraction and the stresses it creates. Nuclear reactor pressure vessels are threatened by overly rapid cooling, and although none have failed, several have been cooled faster than considered desirable.

Biological cells are ruptured when foods are frozen, detracting from their taste. Repeated thawing and freezing accentuate the damage. Even the oceans can be affected.

A significant portion of the rise in sea level that is resulting from global warming is due to the thermal expansion of sea water. Metal is regularly used in the human body for hip and knee implants. Most implants need to be replaced over time because, among other things, metal does not bond with bone. Researchers are trying to find better metal coatings that would allow metal-to-bone bonding. One challenge is to find a coating that has an expansion coefficient similar to that of metal.