A wire under stress

A steel wire of length 1.92 m with circular cross section must stretch no more than 0.210 cm when a tensile (stretching) force of 390 N is applied to each end of the wire.

What minimum diameter is required for the wire?

Express your answer in millimeters. Take Young's modulus for steel to be Y = 2.00×10^11 .

 PhysOrg.com science news on PhysOrg.com >> Front-row seats to climate change>> Attacking MRSA with metals from antibacterial clays>> New formula invented for microscope viewing, substitutes for federally controlled drug
 Recognitions: Gold Member Homework Help Science Advisor Hello, johntuan! Welcome to PF! But per forum rules, before you receive help, you must show an attempt at a solution . Then we can provide assistance to help you obtain the solution, by seeing were you may have gone wrong. You should be familiar with the stress vs. strain or load versus elongation relationship for wires with given parameters of length, load, area, and Young's modulus.
 E=Stress/Strain E=(force/area)/(Change in length/original length) E*(change in length/original length)= force/area area=force/(E*(change in length/original length)) PiR^2=(390N)/((2.0*10^11)/(0.0021m/1.92m)) R^2=((390N)/((2.0*10^11)/(0.0021m/1.92m)))/Pi R=sqrt{((390N)/((2.0*10^(11))/(0.0021m/1.92m)))/Pi d=2R then change into mm

Recognitions:
Gold Member
Homework Help