A certain man has a mass of 79 kg and a density of 991 kg/m 3 (excluding the air

Question

A certain man has a mass of 79 kg and a density of 991 kg/m3 (excluding the air in his lungs).

Randomized Variablesm = 79 kg
? = 991 kg/m3 Part (a) Calculate his volume in cubic meters.
Part (b) Find the buoyant force, in newtons, that air exerts on him. Use 1.29 kg/m3 for the density of air. Part (c) What is the ratio of the buoyant force to his weight? A certain man has a mass of 79 kg and a density of 991 kg/m3 (excluding the air in his lungs).

Randomized Variablesm = 79 kg
? = 991 kg/m3 Part (a) Calculate his volume in cubic meters.
Part (b) Find the buoyant force, in newtons, that air exerts on him. Use 1.29 kg/m3 for the density of air. Part (c) What is the ratio of the buoyant force to his weight?

Explanation / Answer

A. Volume = mass/density = 79 kg/ 991 kg/m3 = 0.07971 cum Ans.

B.

the buoyant force is the weight of the fluid displaced

so the volume of the person is volume = mass/density

mass =79 kg

volume = 0.07971 cum

the density of air is approximately 1.29x kg/m^3, so the mass of air displaced is

mass of displaced air = density of air x volume of person
mass of displaced air = 1.29xkg/m^3 x 0.07971m^3=0.1028 kg

buoyant force = 0.1028kg x 9.8m/s/s = 1.0077 N As.

C. ratio of Buoyant force to weight = 1.0077/79*9.8 = 0.00130 Ans.

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