- #1
Bassel
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why is when working with Bernoulli equation the absolute pressure that we are NOT looking for has a gauge pressure = 0 and only atmospheric pressure while the one we are looking for has both? is this a rule somehow ?
Bernoulli Eqn: Gauge vs Atm Pressure?
- Thread starter Bassel
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In summary, when using the Bernoulli equation, the absolute pressure that is not being looked for is equal to the atmospheric pressure and has a gauge pressure of 0. The absolute pressure that is being looked for has both atmospheric pressure and gauge pressure. This is a rule that is applied in problems such as finding the gauge pressure on one side while the other side is at atmospheric pressure. This is demonstrated in the solution when the gauge pressure on the right side is 0 and the water is at atmospheric pressure.
- #2
tiny-tim
Science Advisor
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Hi Bassel! 
I don't understand.
I don't understand.
Can you give an example?
- #3
Bassel
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the last part of the problem
the last part of the problem by taking the absolute pressure of the right side equal to the atmospheric pressure only by taking the gauge pressure there as 0 while in the left part we are asked to find the gauge pressure. how come one has no gauge and the other has
the last part of the problem by taking the absolute pressure of the right side equal to the atmospheric pressure only by taking the gauge pressure there as 0 while in the left part we are asked to find the gauge pressure. how come one has no gauge and the other has
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tiny-tim
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the question says that the water on the right goes out into the atmosphere
so it is at atmospheric pressure, ie the gauge pressure is 0
so it is at atmospheric pressure, ie the gauge pressure is 0
1. What is the Bernoulli equation and how is it used?
The Bernoulli equation is a fundamental equation in fluid mechanics that describes the relationship between the pressure, velocity, and elevation of a fluid in motion. It is used to understand and predict the behavior of fluids in various applications, such as in pipes, pumps, and wings of airplanes.
2. What is the difference between gauge pressure and atmospheric pressure?
Gauge pressure is the pressure measured relative to atmospheric pressure, which is the pressure exerted by the Earth's atmosphere. Gauge pressure can be positive or negative, depending on whether the pressure is higher or lower than atmospheric pressure. Atmospheric pressure is typically defined as 1 bar or 14.7 pounds per square inch (psi) at sea level.
3. How does the Bernoulli equation apply to gauge pressure and atmospheric pressure?
The Bernoulli equation takes into account both gauge pressure and atmospheric pressure when describing the behavior of a fluid. It considers the total pressure, which is the sum of the gauge pressure and atmospheric pressure. This is important in applications where the fluid is moving or changing elevation, as the pressure will vary along the flow path.
4. What are some real-world examples of the Bernoulli equation in action?
The Bernoulli equation has many practical applications. Some common examples include the flow of water through a pipe, the lift force on an airplane wing, and the operation of a carburetor in a car's engine. It is also used in weather forecasting and the design of hydropower plants.
5. Are there any limitations to the Bernoulli equation?
While the Bernoulli equation is a powerful tool for understanding fluid behavior, it does have some limitations. It assumes that the fluid is incompressible, inviscid, and flows at a steady state. These assumptions may not hold true in all real-world situations, so the results from the Bernoulli equation should be interpreted with caution and verified through experiments or more complex mathematical models.
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