Question

3. A steel tod of length 100 om is fixed at one end and 5 kg load is suspended at the other
end. Calculate the depression if the Young's modulus is 8x 10" Pascals. (Diameter
1.0 cm) (ans, 4.16 cm)​

Answer 1

Given : l=25cm=0.25m,A=0.8cm2=0.8×10−4m2,α=10−5/oC,Y=2×1010N,Δt=10oC .

The coefficient of thermal linear expansion is given by:

            α=l×ΔtΔl 

            lΔl=α×Δt

            lΔl=10−5×10=10−4 

Now, Young's modulus of steel rod is given by:

           Y=A×ΔlF×l 

whee F= force required to stretch the rod of cross section area A length l by Δl

           F=lYAΔl

           F=2×1010×0.8×10−4×10−4=160N

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