A gate automatically opens when the water gets too high.
A) 0.6 m
B) 1.2 m
C) 1.8 m
D) 2.4 m

Question

A gate automatically opens when the water gets too high. 
A) 0.6 m 
B) 1.2 m 
C) 1.8 m 
D) 2.4 m

Quizplus · Accepted Answer

$1.2 \mathrm {~m}$
The force of the water on the vertical gate acts at the hinge just as the gate is about to open. If the force moves above the hinge, the gate will open. The distance $0.6 \mathrm {~m}$ below the hinge means that the water surface is $2 \times 0.6 = \underline { 1.2 \mathrm {~m} }$ above the hinge for the gate to open. See Fig. 2.10.

A Gate Automatically Opens When the Water Gets Too High