# I need help with Fluid systems question

1. May 12, 2013

### StudyNinja1

1. The problem statement, all variables and given/known data

Water is retained in a 1.25 rectangular section channel by a sluice gate. This gate can pivot about its base, the depth of the water is 1.5m and the density of the water is 1000kgm^-3. You must find the tension in the horizontal retaining cable attached to the top of the gate.

2. Relevant equations

Thrust: F= pgAh
Gravity = 9.81

3. The attempt at a solution

Provided data:
Retained water 1.25
Density: 1000kgm^-3
Depth: 1.5m
Gravity: 9.81

So this is what i did, first i found the thrust of the gate so:
F=1000 x 9.81 x 1.5 x 1.25 = 18393.75 so 18.3 x 10^3 or 18.3 kN

I'm not sure though if this is right or what to do next to find the tension, could someone help me on this please

2. May 12, 2013

### voko

The formula for thrust is correct only if the gate is horizontal at the bottom of the channel. From the description, however, it appears that that the gate is vertical.

The problem is that of statics, with a distributed load applied to a vertical bar hinged at the bottom, and a point force provided by the cable.