Need Hmwk HelpFluid mechanics, Fluids in Motion, Pressure

In summary, this conversation is about a physics homework problem involving a syringe filled with water at 20 degrees celsius. The question asks for the gauge pressure of the water at a specific point in the syringe. The suggested approach is to use Bernoulli's equation and apply it to two points where there is the most information, and then use the volume continuity equation to find the speed of the piston. The final answer is 3200 Pa, but the process of arriving at this solution is still unclear.
  • #1
LBRRIT2390
29
0
College Physics

Homework Statement



The figure shows a syringe with a 4.0-cm-long needle, filled with water at 20celsius.
What is the gauge pressure of the water at the point P, where the needle meets the wider chamber of the syringe?

http://session.masteringphysics.com/problemAsset/1014207/7/jfk.Figure.P13.38.jpg


Homework Equations



Bernoulli's Equation


The Attempt at a Solution


I haven't even reached a solution yet because I am totally lost...
I just need some guidance/help working through the problem.
 
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  • #2
The answer is 3200 Pa.

However, I do not know how to arrive at that solution. I'd reallllyyyyy appreciate it if someone could walk me through it, step by step.
 
  • #3
Use Bernoulli's principle. Apply it to the two points where you have the most information: just outside the narrow tube, and very near the piston. You can figure out the speed of the piston from the volume continuity equation.
 

What is fluid mechanics?

Fluid mechanics is the study of how fluids, which include liquids and gases, behave and interact with each other and with solid objects when they are in motion or at rest. It involves understanding the fundamental principles and laws that govern the behavior of fluids, as well as the mathematical equations used to describe and predict their behavior.

How do fluids move?

Fluids move in response to forces acting on them, such as gravity, pressure, or external forces. The motion of fluids can be described using principles of fluid dynamics, which take into account factors such as viscosity, turbulence, and density. These principles can be applied to a wide range of phenomena, from the flow of water in a river to the movement of air around an airplane wing.

What is pressure?

Pressure is the force per unit area exerted by a fluid on its surroundings. It is a measure of how much force a fluid is exerting on a given area, and is typically measured in units of pascals (Pa) or pounds per square inch (psi). In fluid mechanics, pressure is an important concept that helps us understand how fluids behave and how they interact with their surroundings.

How is pressure related to fluid motion?

In fluid mechanics, pressure is closely related to fluid motion. This is because pressure differences between different areas of a fluid can cause the fluid to move from areas of high pressure to areas of low pressure. This is known as the pressure gradient force, and it is responsible for many important phenomena, such as the flow of water through pipes and the circulation of air in the atmosphere.

What are some real-world applications of fluid mechanics?

Fluid mechanics has many practical applications in our daily lives. Some examples include designing efficient pumps, turbines, and other equipment for moving fluids; developing weather prediction models to understand atmospheric circulation and predict storms; and studying the flow of blood in the human body to design better medical devices. Fluid mechanics also plays a crucial role in industries such as aviation, transportation, and energy production.

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