91Ó°ÊÓ

What force must be applied to detach two wetted photographic plates \(9 \mathrm{~cm} \times 12 \mathrm{~cm}\) in size from cach other without shifting them? The thickness of water between the plate is \(0.05 \mathrm{~mm}\). Surface tension of waler is \(0.0073 \mathrm{~N} / \mathrm{m}\). (a) \(31.5 \mathrm{~N}\) (b) \(16.5 \mathrm{~N}\) (c) \(40.5 \mathrm{~N}\) (d) \(20.0 \mathrm{~N}\)

A liquid in a container is rotated about a vertical axis with constant angular velocity \(\omega\). If density of liquid be \(\rho\) and \(r\) is the radius of the container then discuss the variation of pressure in radial and vertical directions, (i.e., pressure in a rotating frame)