Question

A wooden rod of a uniform cross section and of length $120cm$ is hinged at the bottom of the tank which is filled with water to a height of $40cm$. In the equilibrium position, the rod makes an angle of ${60}^o$ with the vertical. The center of buoyancy is located on the rod at a distance (from the hinge) of:

• A. $20cm$
• B. $40cm$
• C. $60cm$
• D. $75cm$

Answer 1

The correct option is B $40cm$

center of buoyancy is at the place where the center of mass ( part of the rod which is under the water) lies.

since 80 cm of the rod is under water.

so, center of buoyancy is at a distance of 40 cm from the hinge.