What is Thermal expansion: Definition and 276 Discussions

Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. Substances which contract with increasing temperature are unusual, and only occur within limited temperature ranges (see examples below). The relative expansion (also called strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As energy in particles increases, they start moving faster and faster weakening the intermolecular forces between them, therefore expanding the substance.

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  1. M

    Linear Expansion: Why Not Volume Expansion?

    Hi, I want to ask one question about linear expansion. For eg if we take tke railway rails. then during summer due to the incresing heat the length of the rails increase. Now anything which has a mass has a volume so when the temperature of the metal rails increase during summer...
  2. B

    Thermal expansion and keeping time

    HI, this problem is supposed to be easy but I don't get it: The coefficient of thermal expansion for Invar is 0.70*10-6K-1. ( Invar is a steel alloy). Given that an Invar pendulum clock keeps perfect time at a room temperature of 20 degree celcius, how much time will the clockgain or lose...
  3. Cyrus

    Does Thermal Expansion Occur Uniformly in All Directions?

    Q: For thermal expansion, does the expansion/contraction take place along all directions uniformly, assuming the material is isotropic and homogeneous? I've had some problems in materials where a change in temperature causes axial changes in length and a different problem where it was diametric...
  4. S

    Thermal Expansion in an aluminum plate

    Question 1: A hole in an aluminum plate has a diameter or 1.178 cm at 23.00 degrees Celsius. (A) What is the diameter of the hole at 199.0 degrees Celsius? (B) What temperature is the diameter of the hole equal to 1.176 cm? For (A) I used the equation Change in Area = 2 * alpha * A *...
  5. D

    Thermal expansion of steel tape

    A steel tape measure gives the length of a brass rod 102cm when both are at 12 degree C. What would the tape measure read (d) when the temperature increases to 45 degree C? coeff of linear expansion of steel = 1.9 * 10 power -5 coeff of linear expansion of brass = 1.1 * 10 power -5 so this...
  6. K

    Thermal Expansion Problem: Help Solve Clearance Issue

    Thermal Expansion Please Help! I have a Thermal Expansion problem that I am having trouble with... It goes : A brass rod has a circular cross section of radius .5 cm. The rod fits into a circular hole in a copper sheet with a clearance of .010 mm completely around it when both it and the...
  7. T

    Separate Brass & Aluminum Rods: Thermal Expansion

    A brass ring of diameter 10.00cm at 20C is heated and slipped over an aluminum rod diameter 10.01cm at 20C. Assuming the average coefficients of linear expansion are constant, to what temperature must the combination be cooled to separate them? what i was thinking of doing here is setting up...
  8. F

    2 more thermal expansion questions

    1.) a steel rod is 3 cm in diameter at 25 C. a brass ring has an interior diameter of 2.992 cm at 25 C. at what common temperture will the ring just slide into the rod? for this Q, i am not too sure which equation to use. i think it's the volume change one, which is delta V= beta(Vo)(delta T)...
  9. F

    Coefficient of linear thermal expansion of a composite bar

    question: a composite bar of length L=L1+L2 is made from a bar of material 1 and length L1 attached to a bar of material 2 and length L2. show that the effective coefficient of linear thermal expansion is : alpha= (a1L1+a2L2)/L [- alpha/a=coefficient of linear thermal expansion] i...
  10. maverick280857

    What is the Mathematical Treatment of Thermal Stress and Strain?

    Hello everyone My query is regarding the following problem: A barometer reads 75.0 cm on a steel scale. The room temperature is 30 degrees C. The scale is correctly graduated for 0 degrees C. The coefficient of linear expansion of steel is \alpha = 1.2 * 10^{-5} per degree C and the...
  11. T

    How to derive the coefficient of thermal expansion?

    Hi! How to relate the Young's Modulus with the coefficient of linear thermal expansion? It is known that they are inversely proportional to each other, but how to prove this?
  12. T

    Why Does Concrete Contract Differently in Cold Temperatures?

    Got this question wrong on this weeks physics quiz and can't figure out why. I keep getting the same answer - which was wrong - over and over. What am I missing? By how much will a slab of concrete 18 m long contract when the temperature drops from 24 °C to -16 °C? (The coefficient of linear...
  13. W

    What is the linear thermal coefficient of expansion for the container?

    I have tried this question 6 times (getting the same answer more than once) and am still not getting the correct answer. I think I need some help understanding where I'm going wrong. The question: A container is filled to the brim with 1.35 L of mercury at 20°C. When the temperature of...
  14. R

    How do I determine the number of fringes in Thermal Expansion Lab?

    Thermal Expansion Lab I'm trying to do the Prelab question 2 in the above lab. These are the steps I'm taking, please correct me if I am wrong, and please assist me where I need help, thanks! 1) The expansion coefficient of copper is 16.7*10^-6 K^-1, and the length of the bar of copper...
  15. R

    Thermal expansion of a metal plate

    Hi guys ,I am stuck up with the following problem,can you please give me a solution. When a metal plate with a circular hole at its centre, is heated, definitely along with the areal expansion of the plate the diametre of the circular hole also increases .But can you give...
  16. R

    Thermal expansion of steel pipe

    The equatorial radius of the Earth is about 6370km. Consider a 40,000 km long steel pipe that forms a giant ring that fits snugly around the equator of the earth. Suppose the temp. of the pipe is increases 1 degree C. The pipe gets longer. it is also no longer snug. How high does the pipe stand...
  17. K

    Thermodynamics - Thermal Expansion

    The following questions are extracted from "Physics" Halliday Resnick & Krane Chapter 21 problem 7. (a) Show that if the lengths of two rods of different solids are inversely proportional to their respective coefficients of linear expansion at the same initial temperature, the difference in...
  18. B

    How Does Thermal Expansion Affect the Tension in a Stainless Steel Band?

    The band below is stainless steel (coefficient of linear expansion=17.3X10^-6 degrees C, youngs modulus=18X10^10 N/m^2). It is essentially circular with an intial mean radius of 5.0mm, a height of 4.0mm and a thickness of 0.50mm. If the band just fits snugly over the tooth when heated to a...
  19. C

    Thermal expansion of lead sphere

    Hi guys and girls, I've been going thorugh some problems in cutnell & johnson on heat and temperature and I have become stuck on this question. Can anybody help with this? Its from Cutnell and Johnson 5th p375 Q18*. A lead sphere has a diatmeter that is 0.05% larger than the inner diameter...
  20. A

    Another problem on Thermal Expansion

    A beaker made of ordinary glass contains a lead sphere of diameter 4 cm firmly attached to its bottom. At a uniform temperature of -10 degrees Celsius, the beaker is filled to the brim with 118 cm^3 of mercury, which completely covers the sphere. How much mercury overflows from the beaker if the...
  21. A

    How Cold to Separate a Heated Brass Ring from an Aluminum Rod?

    A brass ring of diameter 10.00 cm at 20 degrees Celsius is heated and slipped over an aluminum rod of diameter 10.01 cm at 20 degrees Celsius. Assuming the average coefficients of linear expansion are constant, a) to what temperature must this combination be cooled to separate them? b) What if...
  22. J

    What Is the Net Force on Each Side of a Heated Sealed Box?

    thermal expansion? I need help asap! the question goes like this... A cubic metal ox with sides of length 20cm contains air at pressure of 1 atm and a temperature of 300K. the box is sealed so that the volume is constant and heated to 400K. what is the net force on each side of the box...
  23. J

    Thermal expansion and a pendulum clock

    I need a little help. The problem is as follows: A pendulum clock with a pendulum made of brass is designed to keep accurate time at 18 °C. If the clock operates at 0.0°C, what is the magnitude of its error, in seconds per hour (use a minus sign to indicate slowing down)? The linear...
  24. T

    Thermal expansion of diameter of pipe filled with water

    I would like to calculate the new diameter and thickness of a steel pipe filled with water. At 20oC the pipe ID is 0.1016m and thickness is 0.0127m. Coef vol th exp water 21e-5/oC coef lin th exp steel 1.2e-6 The pipe can be assumed 1m in length. I calculated that the water would expand...
  25. A

    Thermal Expansion of copper sphere Problem

    This one is giving me trouble because I don't know the final radius and I don't know how to find it. 1. A copper sphere of radius 2.000 cm is placed over a hole of radius 1.990 cm in an aluminum plate at 20 deg. C. At what common temperature will the sphere pass through the hole? Ans. 747...
  26. S

    Thermal Expansion of a hollow aluminum cylinder

    I need help with coming up with a formula for this question: A hollow aluminum cylinder 18.0 cm deep has an internal capacity of 2.000 L at 18 C. It is completely filled with turpentine and then warmed to 84 C. How much turpentine overflows? If the cylinder is then cooled back to 18 C, how...
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