As, the formula of Reynold’s number Re=ηVcρD
So, the dimension of Re=[ML−1T−1][M0LT−1][ML−3T0][M0LT0] ⇒[Re]=[M0L0T0]
Hence, it is a dimensionless quantity.
Whereas dimension of
(i) Coefficient of viscosity =[M0L−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.