Engineering Board Exam Reviewer · Fluid Mechanics · hard
A vertical rectangular gate 1.2 m wide and 2 m high is hinged at its top edge, which is 3 m below the water surface. What horizontal force applied at the bottom edge is needed to hold the gate closed?
- 94.18 kN
- 47.09 kN
- 51.01 kN
- 102.02 kN
Answer
C. 51.01 kN
Solution
F = hA = 9.81(4)(2.4) = 94.18 kN. yp = 4 + (1.2 × 23/12)/(2.4 × 4) = 4.0833 m, i.e., 1.0833 m below the hinge. ΣMhinge: P(2) = 94.18(1.0833) P = 51.01 kN.
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