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How much is it lengthened from its untensioned length of 30.2 cm?

  • Thread starter mathcrzy
  • Start date
  • #1
47
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Homework Statement



A nylon tennis string on a racket is under a tension of 245 N. If its diameter is 0.92 mm, by how much is it lengthened from its untensioned length of 30.2 cm?

Homework Equations



F=E(delta L/L initial)A

The Attempt at a Solution



245N=(5e9)(?/30.2)(.0266)

delta L = 6.1e-8cm
 

Answers and Replies

  • #2
mgb_phys
Science Advisor
Homework Helper
7,774
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You know the stress, to find the strain you need to know Young's modulus for Nylon.
That is the ratio of the stress to the strain ( can't remember which way round )
 
  • #3
47
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elastic modulus for nylon is 5e9
 
  • #4
158
0
that seems right. does that not match with the answer? Its been a while since i used that equation
 
  • #5
434
0
So you'll want to convert the diameter and the "untensioned length" to meters. Also, you want to think of the cross sectional area as the area of a circle, which you know the diameter of. Does that help?
 
  • #6
158
0
oh ya it has to be in meters. and mm is 1x 10^-3 meters.
 

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