Question

The correct relation between joule and erg is:

• A. $1J={10}^{-5}erg$
• B. $1J={10}^{5}erg$
• C. $1J={10}^{-7}erg$
• D. $1J={10}^{7}erg$

Answer 1

Answer: (D)

$1J={10}^{7}erg$

Joule and erg both are units of work done. An erg is the amount of work done by applying a force of one dyne for a distance of one centimeter. In the CGS base units, it will be one gram centimeter-squared per second-squared. Whereas joule is the amount of work done by applying a force of one newton for a distance of one meter.

Thus,

$1joule=1newton\times 1m$

$1joule=\frac{1kg\times 1m}{1s^2}\times 1m$

$1J=\frac{1000g\times 100cm}{1s^2}\times 100cm$

$1J={10}^{7}erg$

Thus option D is correct.