Calculate thermal stress on an object given its original volume, temperature change, volume change, and bulk modulus. Example 1. Example 2.
Calculating Thermal Expansion: Gas vs. Gas Tank Suppose your Strategy The tank and gasoline increase in volume, but the gasoline increases more, so the amount spilled is the difference in their volume changes.
Example 3. Calculating Thermal Stress: Gas Pressure What pressure would be created in the gasoline tank considered in Example 2, if the gasoline increases in temperature from Insert the known values. Figure 6. Conceptual Questions Thermal stresses caused by uneven cooling can easily break glass cookware.
Discuss the implications of this cell damage for the prospect of preserving human bodies by freezing so that they can be thawed at some future date when it is hoped that all diseases are curable. One method of getting a tight fit, say of a metal peg in a hole in a metal block, is to manufacture the peg slightly larger than the hole. The peg is then inserted when at a different temperature than the block. Should the block be hotter or colder than the peg during insertion?
Explain your answer. Does it really help to run hot water over a tight metal lid on a glass jar before trying to open it? Explain why some materials shrink with increasing temperature. What will its height be on a day when the temperature falls to — Its original height is m and you can assume it is made of steel.
What is the change in length of a 3. How large an expansion gap should be left between steel railroad rails if they may reach a maximum temperature Their original length is You are looking to purchase a small piece of land in Hong Kong. Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise.
To get some idea of the size of this effect, calculate the change in length of a column of water 1. Note that this calculation is only approximate because ocean warming is not uniform with depth. Show that What is their difference in length at Most automobiles have a coolant reservoir to catch radiator fluid that may overflow when the engine is hot.
A radiator is made of copper and is filled to its What volume of radiator fluid will overflow when the radiator and fluid reach their Note that this coefficient is approximate, because most car radiators have operating temperatures of greater than A physicist makes a cup of instant coffee and notices that, as the coffee cools, its level drops 3.
It expands and fits tightly. The expansion and contraction of materials can also cause problems. For example, bridges expand in the summer heat and need special joints to stop them bending out of shape.
When substances expand or contract, their particles stay the same size. Here are five examples:. Simply run some hot water over the metal lid for a few seconds to heat the lid up. This will make the lid expand slightly and it should then be easier to unscrew. This could cause the bridge span 'sections' to buckle. To avoid this, expansion joints are designed into the bridge so that the bridge sections can expand freely without buckling.
Thermometers use the expansion of a liquid such as mercury or alcohol to measure the temperature using a calibrated scale. This to avoid the cables becoming too tight and breaking in cold weather when the cable material contracts. You can sometimes see these cables sag in hot weather. Skip to main content. Temperature and Kinetic Theory. Search for:. Thermal Expansion. Linear Expansion Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.
Learning Objectives Describe volume changes that take place in response to a temperature change. Key Takeaways Key Points Inter-particle potential usually takes an asymmetric form, rather than a symmetric form as a function of particle-particle distance.
This is why matters expands and contracts as temperature changes. The linear expansion coefficient is as an approximation over a narrow temperature interval only.
Key Terms potential : A curve describing the situation where the difference in the potential energies of an object in two different positions depends only on those positions.
Area Expansion Objects expand in all dimensions. Learning Objectives Express the area thermal expansion coefficient in the form of an equation. Just like the linear expansion coefficient, the area thermal expansion coefficient works as an approximation over a narrow temperature interval only.
Key Terms linear thermal expansion coefficient : The fractional change in length per degree of temperature change. Volume Expansion Substances expand or contract when their temperature changes, with expansion or contraction occurring in all directions.
Learning Objectives Compare the effects of the pressure on the expansion of gaseous and solid materials. Key Takeaways Key Points Substances that expand at the same rate in every direction are called isotropic.
In the case of a gas, expansion depends on how the pressure changed in the process because the volume of a gas will vary appreciably with pressure as well as temperature. Key Terms isotropic : Having properties that are identical in all directions; exhibiting isotropy. Special Properties of Water Objects will expand with increasing temperature, but water is the most important exception to the general rule.
Learning Objectives Describe thermal expansion properties of water. Key Terms hydrogen bond : A weak bond in which a hydrogen atom in one molecule is attracted to an electronegative atom usually nitrogen or oxygen in the same or different molecule.
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