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An 10.2-kg stone at the end of a steel (Young's modulus 2.0 x 10^11 N/m2) wire is being whirled in a circle at a constant tangential
speed of 11.6 m/s. The stone is moving on the surface of a frictionless horizontal table. The wire is 3.62 m long and has a radius of
4.10 x 10^-3m. Find the strain in the wire.

Respuesta :

Answer:

[tex]3.6\times 10^{-5}[/tex]

Explanation:

m = Mass of stone = 10.2 kg

v = Tangential velocity = 11.6 m/s

l = Length of wire = 3.62 m

r = Radius of wire = [tex]4.1\times 10^{-3}\ \text{m}[/tex]

A = Area of wire = [tex]\pi r^2[/tex]

Y = Young's modulus of steel = [tex]2\times 10^{11}\ \text{N/m}^2[/tex]

[tex]\varepsillon[/tex] = Strain

The force acting on the stone will be centripetal

[tex]F=\dfrac{mv^2}{l}\\\Rightarrow F=\dfrac{10.2\times 11.6^2}{3.62}\\\Rightarrow F=379.15\ \text{N}[/tex]

Stress is given by

[tex]\sigma=\dfrac{F}{A}\\\Rightarrow \sigma=\dfrac{379.15}{\pi (4.1\times 10^{-3})^2}\\\Rightarrow \sigma=7179488\ \text{N/m}^2[/tex]

Young's modulus is given by

[tex]Y=\dfrac{\sigma}{\varepsilon}\\\Rightarrow \varepsilon=\dfrac{\sigma}{Y}\\\Rightarrow \varepsilon=\dfrac{7179488}{2\times 10^{11}}\\\Rightarrow \varepsilon=3.6\times 10^{-5}[/tex]

Strain in the wire is [tex]3.6\times 10^{-5}[/tex].