A person who weighs 550 N empties her lungs as much as possible and is then completely immersed in water while suspended from a harness. Her apparent weight is now 21.2 N. What is her density?

Question

Quizplus · Accepted Answer

The apparent weight is the actual weight minus the buoyant force. The buoyant force is equal to the weight of the water displaced, which is 550 N - 21.2 N = 528.8 N. The density of water is 1000 kg/m³, so the volume of water displaced is 528.8 N / (9.8 m/s² * 1000 kg/m³) = 0.0539 m³. The person's mass is 550 N / 9.8 m/s² = 56.12 kg. The density is mass/volume = 56.12 kg / 0.0539 m³ = 1040 kg/m³.

A Person Who Weighs 550 N Empties Her Lungs as Much