PhysicsLAB: Test Scenario: Buoyant Force

Refer to the following information for the next six questions.

This scenario is based on the 2002 AP Physics B FRQ #6.

In the laboratory, you are given a cylindrical, graduated beaker containing a fluid and you are required to determine the density ρ of the fluid. You are given some string, a spring of negligible mass, but unknown spring constant k, a ring stand, a ruler, and a object of known mass, m, and density, D.

(a) How would you calculate the object's volume?

(b) Initially, the object is suspended from the spring without making contact with the fluid in the beaker. How could you use the object, mass, and ruler to determine the spring constant?

(c) The object is then lowered and completely submerged into the fluid in the cylinder. How does this affect the length of the spring?

(d) What volume of fluid is displaced by the object when it is submerged?

(f) Draw a free body diagram of the submerged object.

(e) Write an expression for the fluid's density, ρ, that incorporates the spring constant, k, and the density of the object, D.