Question

Find the Buoyant Force on a person with 85% of his body under the water, the density of fresh water is 1000 kg/m^3 (1.0 g/cm^3), the mass of the person is 60 kg and the density of the human body is 985 kg/m^3 (0.85 g/cm^3). Volume of the person =mass / average density of human body

Answer 1

This queston is based on the Concept of Archimedes' Principle.

Before answering the question, let's focus on the fact that the buoyant force is equal to the weight of the liquid/fluid displaced by the object. According to Question,

Given that: Density of fresh water is 1000 kg/m³ (1.0 g/cm³)

Density of the human body is 985 kg/m³ (0.85 g/cm³)

Now, According to Archimedes' Principle,

Since, The mass of person is 60 kg and 85% of his body is under water. Then V_disp is 85% of the Volume of person.

Therefore, Buoyant Force,F_B, on that person can be calculated as:

Hence, The Buoyant Force on the person will be 507.41 N (upward) against a 600 N (downward) Gravitational Force.