Thermal Expansion of brass rod

In summary, the student measures the length of a brass rod at 20.0°C using a steel tape and gets a reading of 80.00 cm. When the rod and tape are at -18.0°C, the tape will indicate a length that is slightly shorter due to the difference in thermal expansion coefficients between brass and steel. The equation used is (delta)L=a*L*(delta)T, where a for brass is 19e-6 and steel is 11e-6. The value for ΔL should be negative in this case.
  • #1
lackos
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Homework Statement


A student measures the length of a brass rod with a steel tape at 20.0°C. The reading is 80.00 cm. What will the tape indicate for the length of the rod when the rod and the tape are at each of the following temperatures?
a) -18.0°C



Homework Equations


(delta)L=a*L*(delta)T.where a for brass is 19e-6, and steel is 11e-6


The Attempt at a Solution


i sarted by finding the change in the increment of a cm on the steel tape using the the above equation and then finding the expansion for a cm of brass at the temperature. multipplied it by the original measurement, then added the resulting value to the measuremnt. however I am not sure if this is right
 
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  • #2
Yes that would be correct. Just make sure your value for ΔL is negative, since your change in temperature is negative.
 

Related to Thermal Expansion of brass rod

1. What is thermal expansion?

Thermal expansion is the tendency of a material to expand or contract in response to changes in temperature. When a material is heated, its molecules vibrate more quickly, causing them to take up more space and expand. Conversely, when a material is cooled, its molecules slow down and contract.

2. How does thermal expansion affect brass rods?

Brass rods, like all materials, will expand when heated and contract when cooled. However, brass has a relatively high coefficient of thermal expansion, meaning it expands and contracts more than other materials in response to temperature changes. This can cause brass rods to expand and contract significantly with changes in temperature.

3. What factors affect the thermal expansion of brass rods?

The thermal expansion of brass rods can be affected by several factors, such as the composition of the brass alloy, the length and thickness of the rod, and the temperature range it is exposed to. Different brass alloys have different coefficients of thermal expansion, with higher percentages of zinc typically resulting in higher expansion. Longer and thicker brass rods will also expand more than shorter and thinner ones. The temperature range is also important, as brass may expand and contract differently at extreme temperatures.

4. How is thermal expansion of brass rods measured?

The thermal expansion of brass rods can be measured using a device called a dilatometer. This instrument measures the change in length of a material as it is heated or cooled. The coefficient of thermal expansion can then be calculated by dividing the change in length by the original length of the rod and the change in temperature.

5. Can thermal expansion cause damage to brass rods?

In extreme cases, thermal expansion can cause damage to brass rods. If a brass rod is exposed to a sudden and significant change in temperature, it can expand or contract too quickly, causing it to crack or bend. This is why it is important to consider the coefficient of thermal expansion when selecting materials for applications that involve temperature changes. However, in most cases, the thermal expansion of brass rods is manageable and can even be beneficial in certain applications.

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