Find the number of erg in one Joule.

Explanation

1 Joule = ? Erg
i.e. `n_(1)u_(1)=n_(2)u_(2)`
`n_(1)=n_(2)[(M_(2))/(M_(1))]^(1)[(L_(2))/(L_(1))]^(2)[(T_(2))/(T_(1))]^(-2)`
or, `n_(1)=1[(1kg)/(1gm)]^(1)[(1m)/(1cm)]^(2)[("1 sec")/("1 sec")]^(-2)`
`=1[(1000gm)/(1gm)]^(1)[(100cm)/(1cm)]^(2)`
`n_(1)=10^(3).10^(4)=10^(7)`
`therefore" 1 Joule "=10^(7)erg`