The dimensions of surface tension are

$Ns$ is the unit of which physical quantity? Write the dimensional formula of momentum.

Turpentine oil is flowing through a tube of length $l$ and radius $r$. The pressure difference between the two ends of the tube is $P$. The viscosity of oil is given by $\eta = \frac{P(r^2 - x^2)}{4vl}$,where $v$ is the velocity of oil at a distance $x$ from the axis of the tube. The dimensions of $\eta$ are

$A$ temperature difference can generate $e.m.f.$ in some materials. Let $S$ be the $e.m.f.$ produced per unit temperature difference between the ends of a wire,$\sigma$ the electrical conductivity and $\kappa$ the thermal conductivity of the material of the wire. Taking $\text{M, L, T, I}$ and $K$ as dimensions of mass,length,time,current and temperature,respectively,the dimensional formula of the quantity $Z=\frac{S^2 \sigma}{\kappa}$ is :-

Dimensions of time in power are

The dimensional formula for Boltzmann's constant is