Hello,

Force acting on a circular disc placed on the surface of water is given by, F = Surface tension * circumference of circular disc. (Equation 1)

Here, Surface tension = 8t dyne/cm

Circumference = 2 * pie * radius = 10 * pie

Substituting the value obtained above in equation 1, we get:

F = 8t * 10 * pie = 80t * pie dyne

F = 80t * pie dyne (Answer)