Question

A circular plate of radius 4cm and weight w is made to rest on the surface of water. If a minimum pull of W+F is required to clear the plate off the water surface then find F. Given surface tension of water Sw=0.072N m-1

Answer 1

$\text{\underline{\underline{Given:}}}$

Radius of the plate = 4 cm = 0.4 m


$\text{\underline{\underline{Therefore,}}}$


Required force,

F = $S_{w}$ × circumference of the plate

F = $S_{w}$ × 2 $\pi \: r$

F $= 0.072 \times 2 \times \pi \times 0.04$

F $= 0.018\:N$


$\text{\underline{\underline{Note:}}}$

Check this attachment.

Answer 2

Answer:

F=0.018N

Explanation:

r=4 cm=0.4m

F=Sw*2pi r

=0.072*2*3.14*0.04

=0.018 N