Bernoulli's equation Definition and 191 Threads

Homework Statement You have been given a milkshake (ρ = 1200kg/m^3). The glass is 200mm tall a straw 8mm diameter and 300mm long. Show that human lungs would be unable to drink the milkshake through a vertical straw. (answer should be around 3000Pa) I have no idea what to do as I don't know...

Hello! I have encountered some trouble with choosing the right reference points when using Bernoulli's equation and I would be glad if you could help me sort it out with this made up example. :) 1. Homework Statement There is a large, open, cylindrical water tank with a cross section area of...

Suppose there are two tanks, tank A and tank B, of equal size and both are very large. Suppose the bottom of tank A is at an elevation that is higher than the top of tank B. Suppose there is a very small tube relative to the size of the tanks that connects the bottom of tank A to the bottom of...

Hi all, I'm considering an fluids example that's giving me an apparent contradiction when I consider it from the perspective of Bernoulli's Equation vs. the Equation of Continuity. What I'm thinking of is the common observation that putting one's thumb over a garden hose results in an increase...

I hope this question doesn't have too obvious of an answer. Basically, I still cannot grasp why Bernoulli's equation applies for wind tunnels and pitot-static probes. According to my textbook ("Introduction to Flight" by Anderson), Bernoulli's equation holds only when comparing two points...

Hi Can anyone advise how the following equation was derived. http://uploadpie.com/PYLrD

(This is more of a conceptual question than a real homework question; thank you all so much for your help though!) :D 1. Homework Statement Let's say that I have a large soda bottle. I drill a small hole through the side of it, put my finger over it to seal the hole, and fill the bottle up...

Homework Statement An incompressible heated gas of constant temperature and pressure flows along an infinitely long tube at an unspecified velocity v1; a pressure of P1; and a density of p1 into an unheated open area of infinite volume containing the same gas at a lower pressure of P2; a...

1. The problem statement, all variables and given/know Say I have a can of water, and I am rotating it about its central axis at a constant angular rate. The water in the tank should make a 3D almost parabolic curve as it touches the the walls of the tank. Can I use Bernoulli's equation along...

Homework Statement A tank of cross-sectional area A is initially filled with fluid of density ρ and viscosity μ to height hi. The pressure above the fluid in the tank is atmospheric, Patm. At the base of the tank there are two pipes, which are both open to teh atmosphere, such that fluid...

Hi, I'm trying to understand vortex shedding and how the Karman vortex street occurs when air flows around a cylindrical object, so far it's going OK but then I came across this part of the explanation which leaves me confused: "Looking at the figure above, the formation of the separation...

Some days ago I got confused trying to solve an exercise about fluid dynamics. Trying to simplify the problem here is a similar situation: I have a cistern connected to a tube containing a fluid as shown in the picture below. Assumming that the fluid is incompressible... I know from the law...

Homework Statement A water storage tank is open to air on the top and has a height of 1 m. If the tank is completely full and a hole is made at the center of the wall of the tank, how fast will water exit the tank? Homework Equations Pressure is the same as atmospheric pressure because the...

Homework Statement Calculate "H" Homework Equations Bernoulli Manometry The Attempt at a Solution I have calculated that Q=0.06723 m^3 /s If I apply Bernoulli in the surface of the tank A and in out of the pipe, I have: H =(velocity in the final part of the pipe^2)/(2g). I have assumed that...

Homework Statement The Plimsoll line is a line marked on the side all ships that effectively indicates the safe maximum load the ship can carry in that type of water at that temperature.You have been asked to stand on the dock and collect the tickets of the passengers boarding a cruise ship...

Hi everyone, I've got a newbie question which is probably more complex than I imagine so please bare with me. As a small DIY project I've trying to build a small exhaust filter system (A) for another device that produces undesirable fumes (B). I'm trying to work out if an axial fan (generates...

hello! I think Bernoulli's equation it's just an equation of conservation of energy. Am I right? but I don't understand how to apply the conservation of energy principle exactly. can you help me please? I get it that if the fluid moves, it has kinetic energy which is 1/2mV^2. I also get...

Homework Statement A wind tunnel is designed to draw in air from the atmosphere and produce a velocity of 100m/s in the test section. THe fan is located downstream of the test section. What pressure is to be expected in the test section if the atmospheric temperature and pressure are -20C...

In the derivation on Wikipedia, it says the following ## \frac{dv}{dt}=\frac{dv}{dx}\frac{dx}{dt}=\frac{dv}{dx}v = \frac{d}{dx}[\frac{v^2}{2}] ## How do they go from the second to last to last equation? I've been trying to understand, but I think I'm just looking over something incredibly simple.

What happens when you have more than one hole in a vessel containing liquid? Can you help me finding the velocities at different holes if they are at some height from level of liquid at a particular instant? I know what happens when you put a small hole in a tank containing liquid at a height h...

1. A sphere 1 ft in diameter is moving horizontally at a depth of 12 ft below a water surface where the water temperature is 50F. Vmax = 1.5Vo, where Vo is the free stream velocity and occurs at the maximum sphere width. At what speed in still water will cavitation first occur? Given: speed...

Homework Statement A pump forces water at a constant flow rate through a pipe whose cross-sectional area, A, gradually decreases. At the exit point, A has decreased to 1/3 its value at the beginning of the pipe. If y= 60 cm(the distance from point 1 to the exit, where point 1 is where y=0)...

I was watering my garden the other day, and I noticed (obviously), that the water came out of the hose faster if I stuck my thumb at the end of the hose. Then I suddenly remembered that in physics class, I was taught that gravity-powered water pressure should result in an exit velocity which...

Definition/Summary Bernoulli's principle is a conservation principle along any streamline of an inviscous flow. It can be expressed as conservation of different types of pressure (force per area) or as conservation of different types of energy per mass. Bernoulli's equation for steady...

So I'm not OK with how some people derive this equation. These people consider a pipe whose endings have cross-sectional areas and heights which are different. They then use the conservation of energy principle by saying dW = dK + dU (Where W is work, K is kinetic energy, and U is potential...

Hi, I haven't done many problems of this nature so there are a few steps in my working that i'd like to check are acceptable/agree with what the question implies. Homework Statement A water tower is a familiar sight in many towns. The purpose of such a tower is to provide storage...

High school student here trying to learn fluids. This is not a homework question, just a concept that I am trying to grasp but can't. The picture below is in my book: The book tells me that the acceleration of the fluid after experiencing the decrease in cross sectional area is due to a...

(1) Hey everyone, I'm only having trouble with part (b) of this problem. I attached a picture of the problem and its diagram. (2) x=vt the x(t) kinematics equations Bernoulli's equation (3) I set the equations for distance as equal: 2√(y1(y2-y1))=2√(y1'(y2-y1')) But I...

Homework Statement For the pipe reducer shown in Figure 6.27 in your textbook, the pressure at point A is 45.8 psig and the pressure at B is 39.5 psig. Calculate the velocity of flow, in ft/s, of the water at point B. State your answer to one decimal place. Example: 25.6 Homework...

Hi everyone, I am currently doing Physics at UNI but I haven't done it in high school. I was wondering if you guys can help me by guiding me on what to do? Much appreciated. I am not doing a Physics Degree. I am doing Physics as an online course as an elective and I have no idea what the...

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 ?

Homework Statement There is a ping pong ball being lifted and suspended in the air by a hair dryer. A.)What is the upward vertical force needed to suspend the ping pong ball? A ping pong ball has a Mass of about 2 grams. B.)If the pressure underneath and inside the ping pong ball is 1 atm...

Homework Statement The following information applies to a conical diffuser: Length = 750 mm Inlet diameter = 100 mm Outlet diameter = 175 mm Water flow = 50 l/s Pressure at inlet = 180 kPa Friction loss = \frac{k(V_{1} - V_{2})^{2}}{2g} where k = 0.15 Calculate the pressure at exit...

Hi all I'm trying to teach myself a bit of bernoulli's principle but i am struggling. I'm pretty sure I need to use a combination of bernies equation and continuity equation but I get lost when trying to rearrange to find velocity. Water moves through a constricted pipe in steady, ideal...

So in a spacecraft with regular air at 1 atm pressure, a hole gets punched in it (depressurizing it). I'm looking for the Exit Velocity of the air at t=0. Using Units: Internal Pressure: Pi = 1 atm = 101300 [kg / m*s2] Air Density: \rho = 1.2 [kg / m3] And Equation: Pi = 0.5 * \rho * (Ve2)...

Homework Statement The Attempt at a Solution Alright so first I found a relationship between z1 (depth of inflow) and z2 (depth of outflow) using mass conservation. I found that 5 * z1 = z2 and I know this is correct because the answer key has the same relationship. Next I decided to...

Homework Statement This is from the notes given to my professor and I think that it may be incorrect: Essentially we have a mercury manometer that measures the pressure difference at points 1 and 2. The fluid flowing through the pipe is water. The goal is to find the height h. Now in these...

Hi! I've been solving problems that apply Bernoulli's equations in *reasonable* situations. One comes from Serway's book. It applies the equation for the force exerted on a window pane in a stormy day. They give us the speed of the wind blowing outside, the area of the window pane, the hint...

My book says: \frac{\partial V}{\partial s}\frac{ds}{dt}=-\frac{1}{\rho}\frac{dP}{ds}-g\frac{dz}{ds} (1.28) The changes of pressure as a function of time cannot accelerate a fluid particle. This is because the same pressure would be acting at every instant on all sides of the...

EDIT: Wow, just realized I skipped a crucial step. Forgot to isolate y' while I was working out the problem and now I see you can't even isolate y' without going back to the original equation. Sorry, disregard the thread please. I'm taking an introductory ODE course (I've only taken up to...

Problem: Suppose the top of a tank is sealed and pressurized to twice atmospheric pressure. What is the speed of the liquid emerging from a small hole at the base of the tank? My Solution: Using Bernoulli's Equation, and assuming v_top ≈ 0, P_top + 1/2*ρ*v_top^2 + ρgh = P_hole +...

In Bernoulli's equation, why the work on fluid at the lower end of the pipe is taken as negative? please explain why the force is negative to displacement at the lower end?

Hi all, please i would like to know physically why when the pressure increase the speed decrease and vice-versa in a flow? Thanks

Homework Statement http://i50.tinypic.com/2m2tbaq.pngHomework Equations The Attempt at a Solution I suppose i have to apply the Bernoulli's equation here but i don't even have the slightest idea on how to apply it here. I am a dumb at fluid mechanics, any help would be appreciated.

Part a is pretty easy m'1+m'2=m'3 m'=mass flow rates density1*velocity1*Area1+(analogous terms for inlet 2)=(analogous terms for inlet 3) The 3 densities are unknown but can be found from equation pressure/(RT) R=286.9 J/(kgk) This gives: density 1=1.66 kg/m^3 density 2=1.432kg/m^3...

Homework Statement A hurricane wind blows across a flat roof (5m x 17.1m) at a speed of 140km/h What is the change in pressure on the roof? (1.28kg/m^3 density of air) Homework Equations Bernoulli's Equation: p1+1/2pv1^2+ pgh1 = p2+1/2pv22 + pgh2 The Attempt at a Solution I...

Homework Statement 2xy'+y^3e^(-2x)=2xy Homework Equations dy/dx + P(x)y=Q(x)y^n v=y^(1-n) The Attempt at a Solution dy/dx-y=-y^3e^(-2x)/2x P(x)=-1 Q(x)=-e^(-2x)/2x n=3 v=1/y^2 dy/dx=dy/dv*dv/dx dy/dx=-1/2v^-(3/2)*dv/dx...

Consider two cylindrical containers of the same diameter. Fill them with a liquid to different levels. We all know that the liquid can be "siphoned" from one container to the other using a thin hose, which we will consider to be thin and of uniform diameter. Bernoulli's Equation can be...

C=v^2/2+gz+ P/p This is it... there is pressure P... and then kinteic energy per unit volume and potential energy per unit volume... adding all of these gives = conservation of energy... Why is this? (Might need to explain the conservation of energy) Preferably a more wordy reply :) thanks

Hi I made up this problem in an attempt to understand the Bernoulli equation better. Homework Statement If there is a constant cross section vent that is open to atmosphere on both sides and have a fan in the middle of the vent, and define state 1 to be at the inlet plane of the vent, state...