Question

A wooden block of mass 10 Kg is floating in water keeping 1/3 of its volume

in air, Find the minimum mass to be placed on the wooden block so that the

block is completely immersed in water.

Answer 1

Here's your answer mate.
Good Luck.

Answer 2

If it floats, the buoyancy has to be greater than the weight. The weigh is easy to compute from the mass (3.5 kg). However, to compute the buoyancy, you need to know the volume of the wood block in addition to the mass (given) and the density of water, which we know is about 998.2071 kg/m^3 at STP.

The weight formula uses Newton's second law (F = m•a) in the form:

w = m • g

where:

w is the weight (force of gravity on a mass)

m is the mass

g is the acceleration due to gravity.

The formula for buoyancy is:

F = V•ρ•g

where

F = buoyant force

V = body volume

ρ = density of fluid

g = acceleration of gravity