The weight of a rectangular block of low-density material is 15.0 $\mathrm{N}$ . With a thin string, the center of the horizontal bottom face of the block is tied to the bottom of a 0beaker partly filled with water. When 25.0$\%$ of the block's volume is submerged, the tension in the string is 10.0 $\mathrm{N}$ .
(a) Sketch a free-body diagram for the block, showing all forces acting on it. (b) Find the buovant force on the four sidewalls of the block that the oil touches. What are the directions of these forces? (d) What happens to the string tension as the oil is added? Explain how the oil has this effect on the string tension. (e) The string break when its tension reaches 60.0 $\mathrm{N}$ . At this moment, 25.0$\%$ of the block's volume is still below the waterline. What additional fraction of the block's volume is below the top surface of the oil? (f) After the string breaks, the block comes to a new equilibrium position in the beaker. It is now in contact only with the oil. What fraction of the block's volume is submerged?