Question

The density of a material in CGS system is $8\, g / cm ^{3}$. In a system of a unit in which unit of length is $5\, cm$ and unit of mass is $20\, g$. The density of material is :-

• A. 8
• B. 20
• C. 50
• D. 80

Answer 1

Answer: (C)

$n _{1} \,u _{1}= n _{2}\, u _{2}$
$\therefore n _{2}= n _{1} \frac{ u _{1}}{ u _{2}}=8\left[\frac{ M _{1}}{ M _{2}}\right]\left[\frac{ L _{2}}{ L _{1}}\right]^{3} $
$=8\left[\frac{1}{20}\right]\left[\frac{5}{1}\right]^{3}=50$