Thermodynamics - Thermal expansion

I understand now that the "beta of mercury" is a constant used to calculate the thermal expansion of mercury. In summary, the question is asking for the amount of mercury that will rise in the capillary tube when the temperature increases by 30 degrees Celsius, given the volume of the bulb and the cross-sectional area of the tube. The thermal expansion of the glass bulb and tube are ignored, and the thermal expansion coefficient of mercury, or "beta of mercury", is given as 1.8 x 10^-4 degreeC^-1.
  • #1
NvZnPhysics
4
0
1. A mercury thermometer has a bulb of volume .100 cm^3 at 10degreesC. The capillary tube (initially empty) above the bulb has a cross-sectional area of .00012 cm^2. How much will the mercury rise when the temperature rises by 30degreesC? Ignore the thermal expansion of the glass bulb and tube. (beta of mercury = 1.8 x 10^-4 degreeC^-1)


Homework Equations


Q = mcdT
H = kAdT/L


The Attempt at a Solution


I tried plugging in numbers for H = kAdT/L and I'm not sure what the "beta of mercury" is. I'm pretty bad at thermo.
 
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  • #2
The "beta of mercury" is the thermal expansion coefficient of mercury, which describes how much the liquid's volume changes with temperature.

Remember: If you are stuck trying to figure out what a given coefficient/constant is for, have a look at the units, here you have units of inverse temperature, so this coefficient MUST describe how something changes with respect to temperature.

Helpful... or do you need more guidance?
 
  • #3
npupp said:
The "beta of mercury" is the thermal expansion coefficient of mercury, which describes how much the liquid's volume changes with temperature.

Remember: If you are stuck trying to figure out what a given coefficient/constant is for, have a look at the units, here you have units of inverse temperature, so this coefficient MUST describe how something changes with respect to temperature.

Helpful... or do you need more guidance?

Thank you so much
 

Related to Thermodynamics - Thermal expansion

1. What is thermal expansion?

Thermal expansion is the tendency of matter to increase in size or volume when heated. This phenomenon is caused by the increase in the average kinetic energy of the particles that make up the material, which causes them to vibrate more and take up more space.

2. What factors affect thermal expansion?

The main factors that affect thermal expansion are temperature and the material's coefficient of thermal expansion. The coefficient of thermal expansion is a measure of how much a material will expand or contract for a given change in temperature. Different materials have different coefficients of thermal expansion, which can also vary depending on the direction of expansion.

3. How is thermal expansion measured?

Thermal expansion is typically measured using a coefficient of thermal expansion, which is expressed in units of length per unit of temperature (e.g. meters per degree Celsius). This coefficient is usually determined experimentally by measuring the change in length or volume of a material as it is heated or cooled.

4. What are some practical applications of thermal expansion?

Thermal expansion has many practical applications, such as in the construction of bridges, buildings, and roads. It is also used in the design of engines, turbines, and other mechanical devices. In addition, thermal expansion is utilized in the production of glass and ceramics, as well as in the calibration of thermometers and other temperature-measuring instruments.

5. How does thermal expansion affect everyday objects?

Thermal expansion can affect everyday objects in various ways. For example, it can cause cracks in roads and sidewalks during extreme temperature changes. It can also cause gaps between the rails of train tracks, which can lead to disruptions in train service. On a smaller scale, thermal expansion can cause objects to become stuck or difficult to open when heated, such as a jar lid or a tight-fitting door.

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