Question

The Young's modulus of a rubber string 8 cm long and density 1.5 $\frac{kg}{m^3}$ is 5 $\times {10}^8\frac{N}{m^2}$. It is suspended from the ceiling in a room. The increase in length due to its own weight will be

• A. $9.6\times {10}^{-5}m$
• B. $9.6\times {10}^{-11}m$
• C. $9.6\times {10}^{-3}m$
• D. 9.6 m

Answer 1

The correct option is B $9.6\times {10}^{-11}m$

b):l = $\frac{L^{2}dg}{2Y}$ = $\frac{(8\times {10}^{-2}{)}^2\times 1.5\times 9.8}{2\times 5\times {10}^8}$ = 9.6$\times {10}^{-11}m$