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Author Question: It is possible to hear an approaching train before you can see it by listening to the sound wave ... (Read 228 times)

jho37

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  • Posts: 531
on: Jul 28, 2018
It is possible to hear an approaching train before you can see it by listening to the sound wave through the track. If the elastic modulus is 2.0  1011 N/m2 and the density of steel is 7.8  103 kg/m3, approximately how many times faster is the speed of sound in the track than in air? (vair  340 m/s.)
 a. 20
  b. 5
  c. 10
  d. 15
  e. 25

Question 2

The Young's modulus for aluminum is 7.02  1010 N/m2 . If the speed of sound in aluminum is measured to be 5.10 km/s, find its density (in kg/m3).
 a. 11.3  103
  b. 7.80  103
  c. 2.70  103
  d. 29.3  103
  e. 1.40  103


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underwood14

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Reply #1 on: Jul 28, 2018
Answer to Question 1

d

Answer to Question 2

c


jho37

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  • Posts: 531
Reply 2 on: Jul 28, 2018
Great answer, keep it coming :)

okolip

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Reply 3 on: Yesterday
Excellent

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