BYU, CHEM 729r

Excerpt: ... it of a fluid at rest pushes outward, perpendicular to any surface or boundary it contacts. b. The pressure at a particular point inside a fluid is the same in all directions. c. Pressure in a fluid increases with depth. In fact, the upward pressure on the bottom of any specified part of the fluid just equals the weight of the fluid directly above. d. The pressure is the same at all points that are at the same depth below the surface of the fluid. Buoyant Force . The buoyant force is the single force that replaces all of the contact forces exerted on an object by the fluid in which it is immersed. The property of the object that is most important in determining the strength of the buoyant force is the submerged volume. Archimedes Principle. An object immersed in a fluid experiences an upward buoyant force . The strength of the buoyant force is equal to the weight (gravitational force) of the displaced fluid. B. 2. 3. C. Applications. 1. 2. Forces on floating objects. A floating object at rest is subject ...

Drexel, PRISM 1

Excerpt: ... BLIMP ENVIRONMENTAL PARAMETER STUDY An important aspect of working with any aerial platform is understanding how it reacts to ambient environmental conditions. Specifically, the dynamics of a blimp are heavily reliant on buoyant force , which is dependent upon the conditions of the environment the blimp is operating in. Perhaps the most volatile of these conditions is the temperature of the ambient air. Characterizing the effect of temperature on buoyant force will pave the way for controlling the blimp in unknown or dynamic environments. The undertaking of studying the effects of temperature on buoyant force of the blimp can be divided into the following tasks: Test Fixture Design, Testing, Data Analysis, and Documentation of Results. TEST FIXTURE DESIGN In order to conduct the test, a test fixture must first be constructed which allows ballast (additional weight) to be incrementally added to the blimp until neutral buoyancy is achieved. The test fixture must be designed such that it does not interfere with n ...

SUNY Buffalo, PHY 101

Excerpt: ... is called the buoyant force : FB = P2 A P1 A = (P2-P1) A = g h A Using that h A=V is the volume of the fluid and that V=m is the mass of the fluid one finds that FB = weight of fluid displaced by the object Physics 101: Lecture 24, Pg 4 Archimedes Principle cont. When does an object float ? An object floats when the upward acting buoyant force is balanced by the downward acting weight of the object: FB = weight of object FB= weight of displaced water => For a floating object: Wobject = Wdisplaced fluid Also Physics 101: Lecture 24, Pg 5 Archimedes Principle (summary) Buoyant Force (FB) Buoyant force = weight of fluid displaced FB = fluid x Vdispl g W = Mg = object Vobject g If object floats. FB=W Therefore fluid g Vdispl. = object g Vobject Therefore Vdispl./Vobject = object / fluid Physics 101: Lecture 24, Pg 6 Concept Question Which weighs more: 1. A large bathtub filled to the brim with water. 2. A large bathtub filled to the brim with water with a battle-ship floating in ...

Washington State, PHYS 201

Excerpt: ... (version 5/31/06) Buoyancy Goals 1) To determine experimentally the relationship between the buoyant force s on objects displacing known weights of water. 2) To compare the buoyant behavior of an object more dense than water with an object less dense than water. 3) To calculate the densities of the aluminum and wood cylinders from your data and compare to handbook values. Introduction Buoyancy is the name given to the force that arises when an object displaces a fluid (either a gas or a liquid) in a force field (usually gravity). A few examples where the buoyant force is obvious include both hot air balloons and fishing bobs. The buoyant force is responsible for keeping ships from sinking. The net force acting on a partially or totally submerged object is the sum of the gravitational force and the buoyant force , which is oppositely directed. This can be written in equation form as FNet = Fg FBuoy The purpose of this lab is to determine the buoyant force acting on objects as they are submerged in water ...

NMSU, TOP 216

Excerpt: ... Worksheet for Exploration 14.3: Buoyancy and Oil on Water This Exploration will address the buoyant force in more depth (pun intended). Specifically, what happens if we put an object in two "layers" of fluids? Assume the brown block is a cube (position is given in meters and pressure is given in pascals). Restart. Note: The format of the pressure is written in short hand. For example 5 atmospheric pressure, 1.01x10 Pa, is written as 1.01e+005. Move the pressure indicator and measure the pressure at the bottom of the wooden block and at the top of the block. a. If the block is a cube, what is the force on the block due to the water ( buoyant force )? i. First sketch a free body force diagram for forces acting on the reshaped box. (One of these is the buoyant force ). Fbuoyant=_ b. What, then, is the weight of the block? What is the density of the block? (Use the symbol Fg as the force due to gravity, ie., weight). Fg=_ density=_ c. Another method: How much (what percentage) of the block i ...

Rutgers, PHYSICS 161

Excerpt: ... 93 material gold iron lead (g/cm3) 19.3 7.86 11.3 material platinum water zinc (g/cm3) 21.4 1.00 6.92 One of the activities described in Part II, is to study how the density of water changes as you dissolve a material in it. Salt is highly ionic and dissociates into Na+ and Cl- ions. Sugar, on the other hand, does not dissociate when it dissolves. Measuring the changes in volume gives you information about the nature of how the salt ions and sugar dissolve in water. Archimedes' Principle states that a body, immersed in a fluid, feels a buoyant force such that: if the body sinks, the buoyant force is just equal to the volume of the body times the density of the fluid. Once the object lies on the bottom of the container, three forces act on it: the buoyant force B, the normal force N (not drawn), and the weight of the submerged object mg. These three forces of course cancel each other because the object stays at rest. Density - 1 =gV mg if the body floats, the buoyant force equals the volume of disp ...

Rutgers, PHYSICS 161

Excerpt: ... 93 material gold iron lead (g/cm3) 19.3 7.86 11.3 material platinum water zinc (g/cm3) 21.4 1.00 6.92 One of the activities described in Part II, is to study how the density of water changes as you dissolve a material in it. Salt is highly ionic and dissociates into Na+ and Cl- ions. Sugar, on the other hand, does not dissociate when it dissolves. Measuring the changes in volume gives you information about the nature of how the salt ions and sugar dissolve in water. Archimedes' Principle states that a body, immersed in a fluid, feels a buoyant force such that: if the body sinks, the buoyant force is just equal to the volume of the body times the density of the fluid. Once the object lies on the bottom of the container, three forces act on it: the buoyant force B, the normal force N (not drawn), and the weight of the submerged object mg. These three forces of course cancel each other because the object stays at rest. Density - 1 =gV mg if the body floats, the buoyant force equals the volume of di ...

CUNY Baruch, PHYSICS 101

Excerpt: ... all directions, but only that normal to the surface doesn't get cancelled out. Net force is normal (perpendicular) to (any) surface. Potential energy of water of mass m = mgh Buoyancy Before studying buoyancy, first study concept of "volume of water displaced" A completely submerged object always displaces a volume of liquid equal to its own volume: Add a rock to a container full of water Volume of water dripped out = volume of rock. Regardless of weight of rock eg. a 1-liter container of milk and a 1-liter container of air submerged in water, both displace the same amount of water. If container is big: then Increase in volume level = volume of rock Buoyancy Buoyant force = upward force acting on an object in liquid, due to pressure on lower part of object being higher than pressure on upper part: Why? Because liquid pressure is larger for larger depths. Question: If there's an upward buoyant force on a submerged object, then how come it doesn't accelerate upwards (N's 2nd law) ? There are also ...

Wisconsin, PHYS 207

Excerpt: ... cture 22, Pg 9 Unusual properties of water q If 4 C water is cooled to freezing temperature in a closed, rigid container what is the net pressure that develops just before it freezes? q B = 0.2 x 1010 N/m2 and V / V0 = -0.0001 F / A0 B =- V / V0 q 0.2 x 1010 N/m2 = P / 0.0001 q 2 x 105 N/m2 = P = 2 atm q Note: Ice B = 9 x 109 N/m2 and the density is 920 Kg/m3 P = 0.08 x 9 x 109 N/m2 or 7 x 108 N/m2 = 7000 atm Physics 207: Lecture 22, Pg 10 Fluids: A tricky problem q A beaker contains a layer of oil (green) with density 2 floating on H2O (blue), which has density 3. A cube wood of density 1 and side length L is lowered, so as not to disturb the layers of liquid, until it floats peacefully between the layers, as shown in the figure. q What is the distance d between the top of the wood cube (after it has come to rest) and the interface between oil and water? q Hint: The magnitude of the buoyant force (directed upward) must exactly equal the magnitude of the gravitational force (directed downward). The ...

Colorado, PHYS 1110

Excerpt: ... The force is perpendicular to the area. Pressure is force/area and has units of N/m2 or pascals (Pa). Atmospheric pressure at sea level is 105 Pa. A fluid doesn't hold its shape and can flow. Liquids are (approximately) incompressible fluids Gases are compressible fluids Fluid mechanics: Hydrostatics Statics is when fluids are not moving The weight of a fluid above causes an increase in pressure as the depth increases. At a depth d below the surface which has pressure p0 in a liquid of density the hydrostatic pressure is p = p0 + gd This also shows that for a connected liquid, the pressure at a given depth is the same no matter where you are. p0 d p Since force is pressure times area, one can use a small area to increase the pressure which can exert a large force over a small area. Hydraulic lifts and hydraulic brakes use this principle. Fluid mechanics: Buoyant force The buoyant force is always equal to the weight of liquid displaced by an object. FB = liquidVdisplaced g An object completely submerg ...

Air Force Academy, P 121

Excerpt: ... = I from f = i + t I = 1 mr22 2 some wrote I = m(r + r ) ? some wrote I = mr + r ? (b) Use s = r1 1 2 2 1 2 2 1 2 2 2 2 1 = i t + 1 t 2 2 Test #2 Notes B5: (a) Use Conservation of Momentum Some tried to us conservation of KE but we cannot assume the collision is elastic (in fact it is not). (b) Use I = Favg t = p Must consider one care only. Not ptot = 0 or pi Proof. Archimedess Principle B The argument works even if the object is not fully submerged. If the volume of the object that is below the surface is V and the density of the fluid is , then, B = Wfluid displaced = Vg Wobject B Wobject Lecture Example 66 Find the fraction of the volume of an iceberg that is under the surface of the water. At 0 C, Density of sea water = 1.03 103 kg/m3, Density of sea ice = 0.92 103 kg/m3. Concept Quiz The wood and iron have equal volumes. The wood floats while the iron sinks. Which has the greater buoyant force on it in the situation shown? wood iron water A ...

Augustana, HELIOS 202

Excerpt: ... Pascal's Principle Pressure applied to an enclosed fluid is transmitted to every portion of the fluid and the container Pascal's principle is the basis for the hydraulic lever Consider a Ushaped tube: If you apply a pressure at one end, the same pressure is felt at the other end But what if the other end of the tube is thicker? A Hydraulic Jack Hydraulic Jack Since the pressures are the same and the areas are different, the force on the other end is larger (from P=F/A) But energy must be conserved: W=Fd, so if the force is greater at the other end the displacement must be less A person can lift a car with a hydraulic jack, but ratcheting the jack 3 feet may only move the car an inch Archimedes' Principle What happens if you put an object in a fluid? The fluid exerts a force on the object The object will also displace fluid If you measure the buoyant force and the weight of the displaced fluid, you find: An object in a fluid experiences an upward buoyant force equal to the weight of f ...