Force to hold nozzle with given flow rate and velocity

In summary, the conversation discusses finding the magnitude of force needed to hold the nozzle of a fire hose stationary while water is being discharged. The attempted solution involves calculating the impulse and momentum of the water being discharged, but does not factor in gravity. The correct solution would be to multiply the mass discharged per second (16 kg/s) by the velocity of the discharged mass (20 m/s) to find the force.
  • #1
kt102188
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Homework Statement



A fire hose discharges water at a rate of 16.0 kg/s with a speed of 20 m/s. What magnitude of force is needed to hold the nozzle stationary?

Homework Equations



Impulse= Change in Momentum, Momentum (p)= mv, velocity final=velocity inital + at

The Attempt at a Solution



V= 20m/s + 9.81m/(s*s)= 29.81
M=(16.0kg)(29.81)
=476.96

Since impulse is the force over time, I thought impulse should be the force needed to keep the hose stationary, but it's not. Any help in where I went wrong would be great! Thanks!
 
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  • #2


Well, first of all I don't see why you're calculating in gravity. Remember, you're only interested in the force as soon as it exits the fire hose.

So, the momentum would just be the mass discharged per second times the velocity of the discharged mass (16*20)
I took the beginning of physics froma really bad teacher and as such spent my calss time talking to my girlfriend and ignoring the class, so I'm fuzzy but it seems that that should be your answer.
 

1. How does the flow rate affect the force required to hold a nozzle?

The flow rate is directly proportional to the force required to hold a nozzle. This means that as the flow rate increases, the force needed to hold the nozzle also increases. This is because a higher flow rate results in a greater amount of fluid passing through the nozzle, which creates a greater force pushing against the nozzle.

2. Does the velocity of the fluid also impact the force needed to hold the nozzle?

Yes, the velocity of the fluid also plays a role in determining the force required to hold a nozzle. Similar to the flow rate, the force is directly proportional to the velocity. As the velocity increases, the force required to hold the nozzle also increases. This is because a higher velocity means that the fluid is moving faster, resulting in a greater force pushing against the nozzle.

3. Is there a specific formula for calculating the force to hold a nozzle with a given flow rate and velocity?

Yes, the formula for calculating the force needed to hold a nozzle is F = ρ * Q * V, where F is the force in Newtons, ρ is the density of the fluid, Q is the flow rate in cubic meters per second, and V is the velocity of the fluid in meters per second. This formula takes into account both the flow rate and velocity of the fluid to determine the force needed to hold the nozzle.

4. Can the force needed to hold a nozzle be reduced?

Yes, the force needed to hold a nozzle can be reduced by using a nozzle with a larger diameter. This is because a larger diameter nozzle allows for a larger flow rate and velocity, which in turn reduces the force needed to hold the nozzle. Additionally, using a nozzle with a smoother surface can also reduce the force needed to hold it.

5. Are there any safety considerations when dealing with high forces to hold a nozzle?

Yes, there are safety considerations when dealing with high forces to hold a nozzle. It is important to use proper safety equipment, such as gloves and goggles, when handling a nozzle that requires a high force to hold. Additionally, it is important to carefully monitor and control the flow rate and velocity to prevent any accidents or injuries from the high force.

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