Bernoulli Equation and Newton Law

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Discussion Overview

The discussion revolves around the application of the Bernoulli equation and Newton's laws to calculate the power required to lift an object using a motor in a tube. Participants explore concepts related to drag force, pressure, and the geometry of the object involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant seeks to calculate the power needed to lift an object with weight W in a tube, questioning the role of friction and the pressure exerted by the motor.
  • Another participant notes that the difficulty of the problem is influenced by the object's geometry, specifically mentioning the coefficient of drag.
  • A later reply indicates a design change, focusing on calculating the drag force on a modified model and asks for hints on solving for the slope area and drag force without using aerodynamic laws.
  • One participant suggests researching Rotameters, indicating their working principle is relevant to the discussion, as it involves equilibrium between gravity and flow forces.

Areas of Agreement / Disagreement

Participants express differing views on the factors influencing the calculations, particularly regarding the geometry of the object and the applicability of Bernoulli's equation in the new context. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants have not reached consensus on the assumptions needed for calculations, including the effects of drag and the specific conditions under which Bernoulli's equation applies. There are also unresolved mathematical steps related to the calculations being discussed.

Who May Find This Useful

This discussion may be useful for individuals interested in fluid dynamics, engineering design, and the application of physical laws in practical scenarios involving forces and motion.

Donny
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Hello friends,

I have a problem in Bernoulli equation and Newton Law. I'm going to calculate how much power is needed to lift up an object with weight W.

I'm planning to put the object in a 10 inches diameter. How can I calculate the power needed by the motor to lift up the object? Does the object has friction in it (the object will float)?

The motor will be placed at the bottom of the tube and will give pressure to the object.

I know that there is also an equation like: F= \frac{P}{A}. but how to implement it? I have my assumption for this one that will happen with the object (Attached). Please correct me if I'm wrong.

Any help means a lot.

Thank you :)
 

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Engineering news on Phys.org
That's a pretty difficult question, because it depends a lot on the geometry of the object - that's where coefficient of drag comes from.
 
Hello Sir!

Thank you for your reply.

I have changed the design, right now I want to calculate drag force on this model (attached).
There are two questions there. The first one could you give me a hint of how to solve the force of the slope area, and the second one is the drag force of the ball ( I don't use a aerodynamic law in here), you can assume the condition to help you give me a hint to solve this problem.

What is the requirements to calculate them? Does Bernoulli Equation is still be used in here?

Thank you.
 

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Try to Google Rotameters (a device which used to measure flow rate). Their working principle is based on equilibrium between gravity forces and the forces from the flow, similar to your model.
check this link for start:
http://www.sensorsmag.com/sensors/Flow+Sensing/The-Basics-of-Rotameters/ArticleStandard/Article/detail/360731
 
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