Question

1 joule = ___ erg.

Answer 1

Work done W by the force F in moving a body through a distance S in the direction of force is given by

W = F x S

SI unit of force is newton (N) and SI unit of distance is meter (m).

So, the SI unit of work done is Nm.

It is also called joule.

1 joule = 1N x 1m

But 1N = 10⁵ dyne and 1 m= 10² cm

Therefore , 1 joule = 10⁵ dyne x 10² cm=10⁷ dyne cm.

dyne cm is the CGS unit of work and is also known as erg,

So 1 joule= 10⁷ dyne cm= 10⁷ erg (1dyne cm= 1 erg)