A cube of mass m and side a, completely wettable by water, floats at the water surface. If water surface tension is s and density is ρw, find the distance h between the lower face of the cube and the undisturbed water surface. Assume contact angle 0°.
Options

Question

A cube of mass m and side a, completely wettable by water, floats at the water surface. If water surface tension is s and density is ρw, find the distance h between the lower face of the cube and the undisturbed water surface. Assume contact angle 0°.

Options

G1 Physics · Accepted Answer

Step 1: Use surface-energy/pressure relations: ΔP = 2T/R for a liquid drop or 4T/R for a soap bubble, capillary rise h = 2T cosθ/(ρgr), and surface energy = TΔA. Step 2: Apply force or energy balance to the stated radii and surface areas. Applying these relations to the given data gives A: h = (mg + 4sa)/(ρw a²g). Final answer: A.