Calculating Force & Pressure for a Reservoir Gate

In summary, the conversation discusses a question about a reservoir with a hinged semi-circle gate that opens to release excess water if the water level exceeds 10 meters. The question is asking for the force required to open the gate and the depth from the free surface to the center of pressure. The conversation also includes the calculation of the second moment of area of the gate and how it relates to calculating the force. The final conclusion is that the force required to open the gate can be calculated using the formula pgh, where p is the pressure, g is the acceleration due to gravity, and h is the height of the water above the gate.
  • #1
adzp
10
0
hi guys.

got another question for ya.
.......

flu1.jpg


seems to of uploaded small but i explain.

a reservoir is designed to retain water to a max depth of 10metres. if the water level exceeds 10 metres, then a hinged semi circle gate will open to release any excess water. the gate has a radius of 1m. the gate is hinged 9 metres below the free surface.

what would be the force required to open gate?

what is the depth from the free surface to the the centre of pressure.

.......

i know the second moment of area of a semi circular surface is 0.1102R4

but not sure how to complete the question. help with working out the answer would be much appraicated so i can work back on the answer and see how to get it.

thanks
adzp
 
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  • #2
In a general sense, you need to calculate the pressure distribution on the gate. From there, using the hinge location, you can use the area to calculate a force on the gate.
 
  • #3
i can't calcluate the area as i do not know all the measurements

or how would i do this?

thanks
adzp
 
  • #4
You know the radius of the gate. That's all you need.
 
  • #5
hi

i have worked out the area and it is 1.571

once i have got the area of the gate, then how to i calculate the force required to open it?

thanks

adzp
 
  • #6
the 2nd moment of area Ig about axis through centroid is 0.1102Rto the power of 4

so that would be 0.1102 x 1.571 to the power of 4 which is 0.272?

still confused where to go next

adzp
 
  • #7
would the force required to open gate be pgh

1000 x 9.81 x 10?

therefore be 98100 pa?

adzp
 

1. What is the formula for calculating the force on a reservoir gate?

The formula for calculating the force on a reservoir gate is F = PA, where F is the force (in Newtons), P is the pressure (in Pascals), and A is the surface area of the gate (in square meters).

2. How do you calculate the pressure on a reservoir gate?

The pressure on a reservoir gate can be calculated by dividing the force acting on the gate by its surface area. This can be represented as P = F/A, where P is the pressure (in Pascals), F is the force (in Newtons), and A is the surface area of the gate (in square meters).

3. What units are used to measure force and pressure?

Force is measured in Newtons (N), and pressure is measured in Pascals (Pa). However, other units such as pounds (lb) or atmospheres (atm) may also be used to measure force and pressure.

4. How does the height of the reservoir affect the force and pressure on the gate?

The height of the reservoir does not directly affect the force or pressure on the gate. However, the height of the reservoir can impact the weight of the water above the gate, which in turn can affect the force and pressure on the gate.

5. Can the force and pressure on a reservoir gate be negative?

Yes, the force and pressure on a reservoir gate can be negative if the gate is pushing against the direction of the force or pressure. This is often seen in scenarios where the gate is being closed and the water is flowing in the opposite direction.

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