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Physics Find force with young modulus

Cbarker1

Active member
Jan 8, 2013
255
Q: Calculate the force (in N) a piano tuner applies to stretch a steel piano wire 8.50 mm, if the wire is originally 0.850 mm in diameter and 1.35 m long. (Young's modulus for steel is 20.0 1010 Pa.)

Work F=Y*A*change in L/L_0

I have no idea what is L_0 and L_f? Please help me.
 

skeeter

Well-known member
MHB Math Helper
Mar 1, 2012
980
$L = 1.35 \, m$

$\Delta L = 8.5 \times 10^{-3} \, m$

$r = 4.25 \times 10^{-4} \, m$

$E=2.0 \times 10^{11} \, N/m^2$


$F = \dfrac{E \cdot \pi r^2 \cdot \Delta L}{L}$