Question

2 You find a large piece of wood sitting next to a pond and decide to whittle (carve) it into a cube of length I. You tie a string around it and tie the other end around a heavy rock and throw both into the pond. When everything comes to rest you notice the wood is just under the surface of the pond. (note: there are no numbers in this problem) a. Using the hydrostatic pressure equation, what is the pressure at the bottom of the cube? What is the force due to your answer in part (a)? Using the hydrostatic pressure equation, what is the pressure at the top of the cube? What is the force due to your answer in part (c)? Subtract your answer in part (d) from part (b). What does the answer correspond to? b. d. e.

Answer 1

The pressure exerted by a fluid at equilibrium at a given point within the fluid due to the force of gravity is Hydrostatic pressure the pressure the pressure = h p g where h is the height to the bottom of cube form bottom of the pond p is the fluid density here g = 9.8 m/s^2 so R = 9.8 times 1063 h pa the force due to the pressure is F = p times area = 9.8 times 10^3 times (surface area of bottom surface) = 9.8 times 1063 l^2 h N to the top of the cube high t = h + l rightarrow pressure P� = (a times 10^3) (h + l) Pa F� = 9.8 times 10^3 l^2 (h + l) N F� - F = 9.8 times 10^3 l^3 N that is weight of a water in a dimension of cube of length �l�