Question

If the volume of a block of aluminium is decreased by 1%, the pressure (stress) on its surface is increased by (Bulk modulus of $ Al=7.5\times {{10}^{10}}N{{m}^{-2}}) $

• A. $ 7.5\times {{10}^{10}}N{{m}^{-2}} $
• B. $ 7.5\times {{10}^{8}}\text{ }N{{m}^{-2}} $
• C. $ 7.5\times {{10}^{6}}N{{m}^{-2}} $
• D. $ 7.5\times {{10}^{4}}N{{m}^{-2}} $
• E. $ 7.5\times {{10}^{2}}N{{m}^{-2}} $

Answer 1

Answer: (B)

Given, $ \frac{\Delta V}{V}\times 100=1%=\frac{1}{100} $
Bulk modulus, $ B=\frac{p}{\Delta V/V}=\frac{pV}{\Delta V} $
Or $ p=\frac{B\Delta V}{V}=7.5\times {{10}^{10}}\times \frac{1}{100} $
$ =7.5\times {{10}^{8}}N{{m}^{-2}} $