⇒[Re]=[M0L0T0] Hence, it is a dimensionless quantity. Whereas dimension of (i) Coefficient of viscosity =[ML−1T−1] (ii) Coefficient of friction =[M0L0T0] (iii) Universal gravitational constant =[M−1L3T−2] (iv) Velocity of light =[M0LT−1] Hence, the dimensional formula of Reynold's number is same as coefficient of friction.