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Thermal Expansion with rod and ruler.

  • Thread starter Aeighme
  • Start date
  • #1
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Homework Statement




A rod is measured to be exactly 21.02 cm long using a steel ruler at a temperature of 21.1oC. Both the rod and the ruler are placed in an oven with a temperature of 340.0oC where the rod now measures 21.32 cm using the same ruler. What is the coefficient of thermal expansion for the material of which the rod is made?

Homework Equations


deltaL=L*alpha*deltaT

deltaL=Change in length
alpha=linear thermal expansion coefficient
deltaT= change in temperature

The Attempt at a Solution



I'm not sure how to solve for alpha of the rod =/
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
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Homework Statement




A rod is measured to be exactly 21.02 cm long using a steel ruler at a temperature of 21.1oC. Both the rod and the ruler are placed in an oven with a temperature of 340.0oC where the rod now measures 21.32 cm using the same ruler. What is the coefficient of thermal expansion for the material of which the rod is made?

Homework Equations


deltaL=L*alpha*deltaT

deltaL=Change in length
alpha=linear thermal expansion coefficient
deltaT= change in temperature

The Attempt at a Solution



I'm not sure how to solve for alpha of the rod =/
I think you need the thermal coefficient of expansion for steel of 13*10-6/C
 
  • #3
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it's either 13E-6 or 11E-6,why 13?

and the ruler is steel and the rod is unknown...
 
  • #4
LowlyPion
Homework Helper
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Last edited:
  • #5
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Thanks,
one more question,
what should I assume the length of the ruler is?
 
  • #6
LowlyPion
Homework Helper
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Thanks,
one more question,
what should I assume the length of the ruler is?

You don't need to know do you?

If you know what the Ruler measures hot. Then you know what it would have measured if the Ruler was cold.

Since you know what the change in length of the Rod is by the change in length from the cold Ruler measurement equivalent, then you know what the coefficient of the Rod is don't you?
 

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