試題詳解

31. A rectangular buoy with cross section A and thickness h floats on the water surface. Jane waits for the buoy to reach static equilibrium and pushes the buoy 1 cm into the water, then releases it. Jane measured that the frequency of oscillation of the buoy was f₁. John did the same experiment, but he pushed the buoy 2 cm into the water. The frequency of oscillation is said to be f₂. It is assumed that the damping is negligible, so only buoyancy and gravity need to be considered. In addition, the density of the buoy is uniform and the buoy is never completely submerged by water. Which of the following statements is correct?
(A)f₁ ＞ f₂ , because the magnitude of the buoyancy force is greater in Jane's case.
(B)f₂ ＞ f₁ , because the magnitude of the buoyancy force is greater in John's case.
(C)f₁ ＞ f₂ , because the magnitude of the buoyancy force is greater in John's case.
(D)f₂ ＞ f₁ , because the magnitude of the buoyancy force is greater in Jane's case.
(E)f₁ =f₂ .