You hang a heavy ball with a mass of 10 kg from a gold wire 2.6 m long that is 1.6 mm in diameter. You measure the stretch of the wire, and find that the wire stretched 1.99 mm. Calculate Young’s modulus for the wire. [Use g = 9.81 m/s2]

Respuesta :

Answer: The Young's modulus for the wire is [tex]6.378\times 10^{10}N/m^2[/tex]

Explanation:

Young's Modulus is defined as the ratio of stress acting on a substance to the amount of strain produced.

The equation representing Young's Modulus is:

[tex]Y=\frac{F/A}{\Delta l/l}=\frac{Fl}{A\Delta l}[/tex]

where,

Y = Young's Modulus

F = force exerted by the weight  = [tex]m\times g[/tex]

m = mass of the ball = 10 kg

g = acceleration due to gravity = [tex]9.81m/s^2[/tex]

l = length of wire  = 2.6 m

A = area of cross section  = [tex]\pi r^2[/tex]

r = radius of the wire = [tex]\frac{d}{2}=\frac{1.6mm}{2}=0.8mm=8\times 10^{-4}m[/tex]      (Conversion factor:  1 m = 1000 mm)

[tex]\Delta l[/tex] = change in length  = 1.99 mm = [tex]1.99\times 10^{-3}m[/tex]

Putting values in above equation, we get:

[tex]Y=\frac{10\times 9.81\times 2.6}{(3.14\times (8\times 10^{-4})^2)\times 1.99\times 10^{-3}}\\\\Y=6.378\times 10^{10}N/m^2[/tex]

Hence, the Young's modulus for the wire is [tex]6.378\times 10^{10}N/m^2[/tex]