The sinking of the cruise ship Lusitania by a German U-boat is often cited as a

Question

The sinking of the cruise ship Lusitania by a German U-boat is often cited as a reason the United States entered WWI. Open portholes were thought to contribute to the vessel sinking in only 18 minutes with the loss of 1, 198 lives. According to author Diana Preston, a prominent marine architect professor from M.I.T. "stated unequivocally that if an open porthole were submerged to a depth of three feet in the conditions of the Lusitania's sinking, it would let in 3.75 tons of water a minute." If h = z_1- z_2 = 3 ft and d = 18 in., estimate the flowrate and compare your answer to the above. State your assumptions.

Explanation / Answer

as the inlet water is from ocean, its safe to assume that the outside water level does not change
mean water level = h + d/2
hydrostatic pressure , Ph = rho*g*(h + d/2)
so the flow velocity through the hole is assumed to be v
the from bernoulli's theorem
Ph = 0.5*rho*v^2 = rho*g(h + d/2)
v^2 = 2g(h + d/2)
h = 3 ft
g = 32.2 ft/s/s
d = 18in = 1.5 ft
v = 15,54 ft/s
Flow rate = rho*A*v = rho*pi*(d)^2*v/4 = 1.71275 lb/s ( rho = 0.0624 lb/ft^3)
in on eminute, water = 102.765 lbs = 0.0513825 tonne
the answer is nowhere close to professor's value

assumptions : sea water is still, and only hydrostatic pressure above the hole is responsible for the gushing water inside

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.