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Speed of sound

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


The speed of sound in the air is proportional to the square root of the absolute temperature. At 20 °C the speed of sound is 343 m/s.

Homework Equations


What is the speed of sound at –10 °C? (0 °C = 273 K).


The Attempt at a Solution


speed of sound= x*[tex]\sqrt{}T[/tex]
x*[tex]\sqrt{}293.15[/tex]=343m/s
x=20.03

so the speed of sound at -10 C (263.15K) is: 20.03*[tex]\sqrt{}263.15[/tex] = 324.92m/s.
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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hi chawki! :smile:

your answer is correct, and your method works, but it will lose you marks in the exam

you do not need to find the value of x

the whole point of questions like this is to see whether you understand this point

you have done this in two steps: you found x, and then you eliminated x …

that is a waste of time (and introduces an opportunity for error)

the correct method (to be used in all "proportionality" cases) is:

speed at -10° C (263.17° K) = 343 x √(263.15)/√(293.15) = 324.92​
 
  • #3
510
0
Ah the yellow fish again :P
Thank you for your help tiny-tim :)
I try to understand your method
 

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