The quantities that are independent of other quantities are called **fundamental quantities**. The units that are used to measure these fundamental quantities are called **fundamental units**. There are four systems of units namely C.G.S, M.K.S, F.P.S, and SI.The quantities that are derived using the fundamental quantities are called **derived quantities**. The units that are used to measure these derived quantities are called **derived units**.**Dimensions** of a physical quantity are the powers to which the fundamental units are raised to obtain one unit of that quantity.

Let dimension of mass in E is=x

Let dimension of mass in V is=y

Let dimension of mass in F is=z

Then, M = Ex Vy Fz

M1L0T0 = [ML2T−2] x [M0L1T−1 ] y [M1L1T−2] z

M1L0T0 =Mx+z L2x+y+z T−2x−y−2z

x+z=1……………(i)

2x+y+z=0………(ii)

2x+y+2z=0…….(iii)

By equation (i), (ii) & (iii)

x=1 y=−2 z=0

**So, [M]=E1V−2 .**