How to apply bernoullie's equation

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In summary, the problem involves a jet of water with a velocity of 10m/s and a cross section of 2cm^2 hitting a flat plate perpendicularly, causing water to splash out parallel to the plate. The goal is to find the force that the plate experiences, given the density of water is 1000kg/m^3. Using the Bernoulli equation, the pressure and area are calculated, resulting in a force of 10N. However, the answer is actually 20N, possibly due to a mistake in the description of the area or the involvement of impulse in the problem.
  • #1

Homework Statement

A jet of water having velocity v = 10m/s and stream cross section = 2cm^2 hits a flat plate perpendicularly, with water splashing out parallel to plate. Find the force that plate experiences.
density of water d=1000kg/m^3

Homework Equations

0.5dv^2 = p

The Attempt at a Solution

on applying berno.. i calculated pressure and then used force = pressure*area
but answer is wrong why?
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  • #2
You say "the answer is wrong"; we need a bit more information. What calculations have you carried out and what answers have you obtained?
  • #3
i calculated pressure = 50000 Area = 2cm^2
force = 50000*(2/10000)=10N
but the answer is 20N
  • #4
Well your equation seems correct and with the values as given so does your answer... My concern is with the description of the area in the question as stated. Is it possible that the questioner intended to write that as an area of [itex]2^2[/itex] cm[itex]^2[/itex] = 4 cm[itex]^2[/itex]? That would account for the factor of two.
  • #5
no the data is correct i think "with water splashing out parallel to plate" is the key point to he problem and this is where i make a mistake while applying Bernoulli
any clue
  • #7
concept of impulse is involved

1. What is Bernoulli's equation?

Bernoulli's equation is a fundamental equation in fluid mechanics that relates the pressure, velocity, and height of a fluid in a steady flow. It states that the total energy of a fluid in a system remains constant as it moves along a streamline.

2. How is Bernoulli's equation used?

Bernoulli's equation is used to analyze fluid flow in a variety of systems, such as pipes, pumps, and airfoils. It is particularly useful for determining the pressure and velocity at different points in a fluid flow, as well as predicting the behavior of fluids in different situations.

3. What are the assumptions of Bernoulli's equation?

Bernoulli's equation assumes that the fluid is non-viscous (frictionless), incompressible, and has a constant density. It also assumes that the flow is steady (not changing with time) and that the energy losses due to friction and turbulence are negligible.

4. How do you apply Bernoulli's equation in a real-world situation?

To apply Bernoulli's equation in a real-world situation, you first need to identify the points in the fluid flow where you want to analyze the pressure and velocity. Then, you can use the equation to calculate the pressure and velocity at each point, taking into account any changes in height or other variables. Finally, you can compare the results to determine the behavior of the fluid in the system.

5. What are some limitations of Bernoulli's equation?

Bernoulli's equation is a simplified model that does not take into account all factors that may affect fluid flow, such as viscosity and turbulence. It also only applies to steady, incompressible flows, so it may not accurately predict the behavior of fluids in all situations. Additionally, it assumes ideal conditions that may not exist in real-world scenarios.