Passage III

When an object is submerged in a fluid, the object dis­places a volume of fluid equal to the object's submerged volume. The fluid exerts an upward buoyant force on the object that is equal in magnitude to the weight of the dis­placed fluid. The object floats if the buoyant force equals the object's weight.

A group of students conducted 2 studies on buoyant forces using 3 fluids一water, Fluid A, and Fluid B一having densities of 1.0 g/cm³, 1.25 g/cm³, and 1.50 g/cm³, respectively.

Study 1

The students placed a 10 cm long cylinder in a con­tainer of water and measured the length o f the portion of the cylinder that was submerged. They then repeated this procedure with a container of Fluid A and o container of Fluid B (see Figure 1).

Study 2

The students placed a stone—either Stone X, Stone Y, or Stone Z—in a net that was tied to a spring balance. They recorded the force measured by the balance as the stone's weight, W. They then submerged the stone in water and again recorded the force measured by the balance (see Figure 2).

The students calculated the buoyant force on the stone in water as W minus the force that was measured when the stone was submerged. They repeated this procedure to test all 3 stones in all 3 fluids. Table 1 lists each stone's volume, in cm³, and W, in newtons (N), as well as the buoyant force, in N, on each stone in the fluid.