AAMC FL Practice Exam

How is the density of a human body calculated?

1. Weight in air

2. Weight in water divided by weight in air

3. Weight in air minus weight in water

4. Weight in water divided by weight in air

The correct answer is: Weight in air minus weight in water

The density of a human body can be accurately calculated using the principle of buoyancy, specifically by measuring the weight difference in air and water. The correct answer involves subtracting the weight of the body in water from its weight in air. This method takes into account the buoyant force that water exerts on a submerged object, which reduces its apparent weight. When a body is weighed in air, it corresponds to its true weight. Upon submersion in water, the buoyant force acting on the body leads to a decrease in weight. The difference between the weight in air and the weight in water directly reflects the volume of water displaced, which is proportional to the volume of the body itself. Thus, by utilizing this weight difference, one can derive the volume of the body and ultimately calculate its density, defined as mass per unit volume. This method is sound because it aligns with Archimedes' principle, which states that the buoyant force on an object is equal to the weight of the fluid displaced by it. By correctly applying this principle through weight measurements, one can effectively determine body density.