Brass Compression: Solving For ΔL

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SUMMARY

The discussion centers on calculating the shortening of a 1.8-meter long brass bar with a square cross-section of 1.3 cm under a compressive force of 9.0×103 N. The formula used is a variation of Young's Modulus, expressed as ΔL = FL/YA. The correct calculation yields a shortening of approximately 0.0011 m, which is close to the online homework program's answer of 0.00105 m. The discrepancy arose from the program's rounding rules, not from the calculation itself.

PREREQUISITES
  • Understanding of Young's Modulus and its application in material science.
  • Familiarity with basic physics concepts such as force, area, and stress.
  • Ability to perform unit conversions, specifically from centimeters to meters.
  • Knowledge of elastic properties of materials, particularly brass.
NEXT STEPS
  • Study the derivation and applications of Young's Modulus in different materials.
  • Learn about the properties of brass and its behavior under stress.
  • Explore the concept of stress and strain in materials science.
  • Investigate the effects of rounding in numerical solutions and how it impacts results in engineering calculations.
USEFUL FOR

Students in physics or engineering courses, materials scientists, and professionals involved in mechanical design or structural analysis will benefit from this discussion.

kboykb
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Homework Statement



A 1.8- m long brass bar has a square cross section 1.3 cm on an edge. The bar is compressed by a force of 9.0×10^3 N applied to its ends. By how much does the bar shorten (in m)?

Homework Equations



There is an example in our book explaining how to use a variation of Young's Modulus. ΔL = FL/YA

The Attempt at a Solution



Change 1.3 cm into .013 m.

(9.0x10^3 N)(1.8m) / (91 x 10^9 N/m^2)(.013^2) = .0011 m

I squared .013 since it's the area squared.. and the 91 x 10^9 is the value for brass in the Elastic Moduli.

Of course this is wrong, but not sure what I'm not doing quite right.
 
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Nevermind guys, that turned out to be the CORRECT answer.

The online Homework program had the answer listed as .00105 m

Since I was putting .0011 in it did not accept my answer. Go figure *sigh*
 

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