Question

If the units of mass, length and time are $100$ g, $20$ cm and $1$ minute respectively the equivalent energy for $1000$ erg in the new system will be:

• A. $90$
• B. $900$
• C. $2\times {10}^6$
• D. $300$

Answer 1

The correct option is A $90$

$Energy=M^1{L}^2{T}^{-2}$

$=100g\times \frac{(20{)}^{2}cm}{(60{)}^{2}se{c}^2}=\frac{1000}{90}erg$

$\Rightarrow 1000$ erg in new system is $\frac{1000}{\frac{1000}{90}}=90$