Whether an object is submerged completely in a fluid or whether it floats on the surface of that fluid, it experiences a buoyant force. Buoyant force is the force of the fluid on the object; it results from pressure differences. In general, buoyant force is written as:
$$
\mathrm{B}=\rho_{\text {fluid }} \cdot \mathrm{V}_{\text {displaced fluid }} \mathrm{g}
$$
A researcher sets up the following experiment: A wooden box of cross-sectional area $A$ and density $r$ is floating on the surface of a fluid, so that a length $L$ of the box is submerged (Figure 1a). A force F is then applied to the top of the box, so that now an additional length $x$ of the box is submerged (Figure 1b).
Figure 1 can't copy
The force F is then removed and the box is observed to bob as a simple harmonic oscillator, where the acceleration a, displacement from equilibrium x , and oscillation frequency $f$ are related by:
$$
\mathrm{a}=-4 \pi^2 f^2 \mathrm{x}
$$
In the following questions, neglect the effects of fluid viscosity.
Buoyant force is always equal to the:
A. weight of the object.
B. weight of the fluid displaced.
C. volume of the object.
D. volume of the fluid displaced.