Archimedes Principle Essays - Fluid Mechanics, Fluid Dynamics

Archimedes Principle Essays - Fluid Mechanics, Fluid Dynamics Archimedes Principle Physics 202 Professor Lee Carkner Lecture 2 PAL #1 Fluids Column of water to produce 1 atm of pressure P = rgh P = r = 1000 kg/m3 g = 9.8 m/s2 h = P/rg = Double diameter, pressure does not change On Mars pressure would decrease Mars has smaller value of g Archimedes Principle What happens if you put an object in a fluid? Called the buoyant force If you measure the buoyant force and the weight of the displaced fluid, you find: An object in a fluid is supported by a buoyant force equal to the weight of fluid it displaces Applies to objects both floating and submerged Will it Float? Density An object less dense than the fluid will float A floating object displaces fluid equal to its weight A sinking object displaces fluid equal to its volume Floating How will an object float? The volume of fluid displaced is proportional to the ratio of the densities Example: ice floating in water, riVig=rwVwg Vw=Vi (ri/rw) rw = 1024 kg/m3 and ri = 917 kg/m3 Ideal Fluids Steady Incompressible density is constant Nonviscous Irrotational constant velocity through a cross section The ideal fluid approximation is usually not very good Moving Fluids What happens if the pipe narrows? Avr = constant If the density is constant then, Av= constant = R = volume flow rate Constricting a flow increases its velocity Because the amount of fluid going in must equal the amount of fluid going out Or, a big slow flow moves as much mass as a small fast flow Continuity R=Av=constant is called the equation of continuity You can use it to determine the flow rates of a system of pipes Cant lose or gain any material The Prancing Fluids How can we keep track of it all? The laws of physics must be obeyed Neither energy nor matter can be created or destroyed Bernoullis Equation Consider a pipe that bends up and gets wider at the far end with fluid being forced through it Wg = -Dmg(y2-y1) = -rgDV(y2-y1) The work of the system due to pressure is, Wp=Fd=pAd=DpDV=-(p2-p1)DV D(1/2mv2)=1/2rDV(v22-v12) p1+(1/2)rv12+rgy1=p2+(1/2)rv22+rgy2 Consequences of Bernoullis Fast moving fluids exert less pressure than slow moving fluids This is known as Bernoullis principle Energy that goes into velocity cannot go into pressure Note that Bernoulli only holds for moving fluids Bernoulli in Action Blowing between two pieces of paper Convertible top bulging out Airplanes taking off into the wind Lift If the velocity of the flow is less on the bottom than on top there is a net pressure on the bottom and thus a net force pushing up If you can somehow get air to flow over an object to produce lift, what happens? Deriving Lift Use Bernoullis equation: pt+1/2rvt2=pb+1/2rvb2 The difference in pressure is: pb-pt=1/2rvt2-1/2rvb2 (Fb/A)-(Ft/A)=1/2r(vt2-vb2) L= ()rA(vt2-vb2) Next Time Read: 15.1-15.3 Homework: Ch 14, P: 37, 42, 47, Ch 15, P: 6, 7 Which of the following would decrease the pressure you exert on the floor the most? Doubling your mass Doubling the mass of the earth Doubling your height Doubling the size of your shoes Doubling air pressure Which of the following would increase the pressure of a column of fluid of fixed mass the most? Doubling the width of the column Halving the density of the fluid Halving the mass of the Earth Halving the speed of the Earths rotation Doubling the height of the column Summary: Fluid Basics Density =r=m/V Pressure=p=F/A On Earth the atmosphere exerts a pressure and gravity causes columns of fluid to exert pressure Pressure of column of fluid: p=p0+rgh For fluid of uniform density, pressure only depends on height Summary: Pascal and Archimedes Pascal pressure on one part of fluid is transmitted to every other part Hydraulic lever A small force applied for a large distance can be transformed into a large force over a short distance Fo=Fi(Ao/Ai) and do=di(Ai/Ao) Archimedes An object is buoyed up by a force equal to the weight of the fluid it displaces Must be less dense than fluid to float Summary: Moving Fluids Continuity the volume flow rate (R=Av) is a constant fluid moving into a narrower pipe speeds up Bernoulli p1+1/2rv12+rgy1=p2+1/2rv22+rgy2 Slow moving fluids exert more pressure than fast moving fluids

10 Hobbies That Look Great On Your Resume

10 Hobbies That Look Great On Your Resume The going advice might  tell you to leave your hobbies off your resume- there isn’t enough space and potential recruiters are most eager to see your skills and experience. But there are a few situations in which adding a few of your hobbies to your resume can actually add value to your candidacy and help you stand out from the crowd. You can and should include any hobby that has some bearing on your proposed job duties, or something that would endear you to a more creative company like Google. Just remember: if you put it on your resume, it’s fair game in the interview.Here are a few hobbies that might actually make things easier for you to land a job.1. YogaBelieve it or not, a dedication to yoga shows a commitment to staying calm and in control. The ability to breathe through tough moments will look like an asset in a fast-paced, high-energy environment. Shows you can handle pressure.2. Extreme AdventureIf your bosses to be are impressed by risk and pushing boundari es without losing your cool, listing extreme adventure sports on your resume can show you have these valuable traits- which might just land you a leadership role.3. Video ProductionDitto any kind of design, especially if you’re going for a gig in production or event planning. Who knows when you might be asked to livestream or broadcast content in the course of a job?4. Endurance SportsThese show dedication, perseverance, and grit. Who doesn’t think these qualities are appealing in a potential hire? Particularly in sales or business roles.5. Creative HobbiesYou like to cook or paint or take photographs, or do any sort of design, you might be in a better position to list these on your resume and appeal to jobs that are not just looking for hard skills, but a little creative je ne sais quoi. 6. Team SportsShow you can be part of a team- especially if your team experience is leaner in the work sphere and you are applying for a team-based job.7. WritingA bit of creative wri ting can both showcase your creative side, but also show your strengths as a writer or editor- both incredibly useful skills in communication for almost any job. It’s a highly sought after skill that most people are just not that great at. Show your stuff!8. Community InvolvementBeing active in your community or volunteering suggests that you are caring, service-oriented, and comfortable with collaboration. You might even show yourself as perfect for a managerial role without even trying too hard.9. BloggingAs long as your blog is professional looking and not too salacious in content, an interest in blogging can be a real asset. Bonus points if your blog matches your online presence/personal brand and if the content is current, well-written, and free of mistakes.10. Playing an InstrumentPlaying an instrument takes talent, yes, but also determination and dogged practice. Show you’re willing to put in the time and commitment to improve, and your future boss just might be lieve you.That being said, while your hobbies are important, it’s also important to build the functional aspects of your resume because that is what will ultimately determine whether or not you get your foot in the door.And one way to make sure your resume is top notch is by keeping up with certain resume trends. If you can keep up with trends, you will be able to keep your resume updated and efficient.