# What is Archimedes' principle: Definition and 48 Discussions

Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse.

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1. ### What kind of pump can do this?

Hello -- I am working on a project where I need to recirculate a fluid which has a large quantity of glass spheres of say, 1mm diameter suspended in it, but without the pump crushing the spheres. I would appreciate any advice. To give a simple description of the desired function: it will be a...
2. ### Pressure in fluids and Archimedes' principle

Hello. A: If we put this piece of wood in the emty container, the volume of displaced water will not change (because Buoyant Force has not changed), so the pressure at the bottom of the water container doesn't change and it remains constant. B: If we put the metal in the emty container, the...
3. ### Pressure difference between the top and bottom surfaces of this cube

Hi all, I think I have to take the formula for pression. rho = F/A -> rho = ma/A but not sure, how to handle it here. I thought, it should be rho under - rho above = pl*L - pc *a Solution is: pl *g *a
4. ### I A specific case of an exception to Archimedes' Principle?

First post on this forum, hopefully in the correct category and conforming to forum rules. Will the object in below scenario move upwards, downwards or will it remain stationary? An object is submersed in a container 'A' which contains a fluid 'B' (e.g. water) The trapezium shaped object...

6. ### I A proof of Archimedes' Principle

Hi All, is there a proof to Arquimedes Principle and the expression for the buoyancy force? In case there is a proof, may we refer to this as Arquimedes theorem? (Buoyancy force = density of the fluid x acceleration of gravity x submerged volume) Best Regards, DaTario
7. ### Buoyant Force and Archimedes' Principle

Hello there, I have a quite different approach on answering the part c and d of this problem. Can you guys help me to see if my method is acceptable or logical? (I got the same answers as the back of the textbook, however my methods differ from the solutions manual). Here is my answer/attempt at...
8. ### General Query on Archimedes' Principle

I had some questions about Archimedes' Principle. This image shows an object being gradually submerged into fluid: As far as I'm aware, when the object is floating, weight of fluid displaced by object = upthrust acting upwards on the object. When the object is fully submerged, volume of the...
9. ### Will the displacement of a solid ball affect the water level?

(The picture below is my drawing. I followed the instructions of the problems and drew for reasons of clarity.) Let me start by writing down the given details : Volume of drum ##V_D = 0.05 m^3##, mass of drum ##m_D = 5 kg##, height of water column (initially) ##h_W = 1 m##, base area of water...
10. ### Gauge pressure due to a floating body

My answer : Both pressures are equal, i.e. ##\boxed{P_A = P_B}##. Reason : (1) The block of wood displaces an amount (mass) of liquid equal to its weight (archimedes' principle for floating bodies, or law of floatation). Hence we can imagine removing the block in the second case and filling it...
11. ### How much sea water is needed to keep a submarine still at 30 meters depth?

Homework Statement A submarine is in water, depth 30 meters. Inside submarine there is default air pressure. Submarine has volume of 125 m³, from which 10 m³ is water tank used for submerging. Submarine weights 123 tons. How large portion of the water tank has to be filled with sea water in...
12. ### Buouyancy force and Archimedes' principle

How much more will the volume of a fishingboat go under water, if I load the boat with 3.0m^3 fish with the density 0.90kg/dm^3? Fish : 3.0m^3 Density of fish: 0.90kg/dm^3? Homework Equations Archimedes principle: density * volume * g[/B]The Attempt at a Solution Tried setting upward force...
13. ### Archimedes' principle -- Which box will sink first as we add coins....

There are five empty box contains with the same weight. The upper side of each boxes are removed. These boxes are floating in a pool of water. Then to each box we put coins slowly one by one. Assuming the box does not tilt. Determine which of the following size of the box (p x l x t) can be...
14. ### B Archimedes' Principle for gases - derivation?

Hi all, I understand where Archimedes' Principle comes from in liquids: If we imagine a cylinder immersed in a liquid of density ρ whose cross-sectional area is A and whose top is at depth h1 and whose bottom is at depth h2: Force(top of cylinder) FT = ρgh1A Force(bottom of cylinder) FB =...
15. ### Using Archimedes' principle in engineering applications

Homework Statement A cylindrical buoy floats in sea water with its axis vertical so that it's three-fourths submerged. The buoy is 0.8m in diameter and 2m in height. Its fabricated from iron plate 10mm thick. Calculate the mass of iron chain securing the buoy. The relative density of iron is...
16. A

### Archimedes' Principle and a weather balloon

Homework Statement 2. Homework Equations Buoyant force= mg(mass of fluid displaced = Vpg (volume of fluid displaced) Buoyant force=weight of object (if floating) The Attempt at a Solution If the total mass is 99kg, then the total force acting downwards is 990N. It also said that the balloon...
17. ### I Something about Archimedes' Principle

Hello, I was reading about Archimedes' Principle on the wiki ( https://en.wikipedia.org/wiki/Archimedes%27_principle ) and a question popped up regarding the upthrusting force (also called buoyant force) that the liquid exerts on an object that is in the liquid. I understand that the...
18. ### What is Archimedes' Principle?

Homework Statement Can somebody please tell me exactly what archimedes prnciple is? Homework Equations The Attempt at a Solution [/B] So, I watched this video: . Apparently if we have a cube in a bucket of water then the mass of the whole cube is equal to the mass of the displaced water...
19. ### I understanding Archimedes' principle.

I want to know why does the buoyant force equal to the weight of fluid displaced and how the weight of water displaced is equal to the weight of object for free floating objects? What's buoyant force by the way?
20. ### Hard Time Understanding Archimedes' Principle.

If I have a body (for simplicity a cube with side d) on a fluid (with density ρ) with its top at a depth h, the force acting on top of it is ma = (h*d*d)*ρ*(g); where g is the acceleration of gravity, (d*d*h) is the volume of the column of liquid on top of the cube and that times ρ is the mass...
21. ### Millikan oildrop experiment: archimedes' principle

Hello! My physics teacher gave me an assignment to work out (theoretically) how Millikan's oildrop experiment works. The simple principle of the experiment (as far as I know): E = \frac{F}{Q} F = mg mg = qE \rightarrow q = \frac{mg}{E} However, after reading a bit on Wikipedia it...
22. ### Confused with the Archimedes' Principle

Archimedes' Principle states: "Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object." If this is true, why then, when you take a bowling ball and submerge it in water, and take a rubber ball of the same size and...
23. ### How does Archimedes' Principle work?

the Archimedes' Principle states that the weight of the fluid displaced is equal to the buoyant force. why/how does that happen?
24. ### Archimedes' principle with 2 liquids

A sphere of density = 500 kg/m^3 floats on water (density of water = 1000 kg/m^3). 1. What fraction of the volume of the sphere is below the waterline? ---I understand this problem and I got the correct answer of 0.5 2. Another liquid of density 200 kg/m^3 is now added on top of the water. The...
25. ### Problem Solving about Archimedes' Principle

Homework Statement A piece of metal weighs 50.0 N in air, 36.0 N in water and 41.0 N in oil. Find the densities of the metal and the oil.Homework Equations Density of Water is 1000 kg / m^{3} Density of Air is 0.00121 g / cm^{3}The Attempt at a Solution I really don't have any idea on how to...
26. ### Finding weight using Archimedes' principle

A rectangular block of solid carbon (graphite) floats at the interface of two immiscible liquids. The bottom liquid is a relatively heavy lubricating oil, and the top liquid is water. Of the total block volume, 54.2% is immersed in the oil and the balance in the water. In a separate experiment...
27. ### How Small Can the Iceberg Get Before the Polar Bear Gets Wet Feet?

Homework Statement A polar bear of mass 520 kg is floating on an iceberg in the ocean. As the ice melts, how small can the iceberg get before the bear gets wet feet? (The answer should be the volume of the iceberg). Homework Equations Buoyant Force, Fb = p(fluid)V g From a table in...
28. ### Problem that (probably) involves Archimedes' principle

Homework Statement Serway book 14.26 The weight of a rectangular block is 15N. With a thin string, the center of the horizontal bottom face of the block is tied to the bottom of a beaker partly filled with water. 25% of the block is submerged when the tension is 10N Oil of density 800...
29. ### How Much Additional Mass Can a Floating Air Mattress Support?

Homework Statement A rectangular waterproof air mattress is 2.0m long, 0.50mwide and 0.08m thick. It has a mass of 2.0kg and is supporting an additional mass of m, while floating in the water, calculate the mass, m, assuming the density of water is 1000kg/m^3 and density of air is...
30. ### Buoyancy and Archimedes' Principle of steel

Homework Statement Because gasoline is less dense than water, drums containing gasoline will float in water. Suppose a 260 L steel drum is completely full of gasoline. What total volume of steel can be used in making the drum if the gasoline-filled drum is to float in fresh water...
31. ### Archimedes' Principle Buoyancy?

Homework Statement A flotation device is in the shape of a right cylinder, with a height of 0.500 m and a face area of 4.00 m2 on top and bottom, and its density is 0.400 times that of fresh water. It is initially held fully submerged in fresh water, with its top face at the water surface...
32. ### Buoyancy and Archimedes' Principle (Helium ballon and cargo problem)

Homework Statement " A spherical balloon has a radius of 7.35 m and is filled with helium. How large a cargo can it lift, assuming that the skin and structure of the balloon have a mass of 930 kg? Neglect the buoyant force on the cargo volume itself." Homework Equations So F(b) = (mass...
33. ### Shape of Nuclear Explosions: Exploring Archimedes' Principle

why do they form the shape they do? that is after a nuclear explosion i'm familiar with thermodynamics and fluids ect..., does it have something to do with archimedes principal?
34. ### Buoyant Forces and Archimedes' Principle

Homework Statement A 62.0-kg survivor of a cruise line disaster rests atop a block of Styrofoam insulation, using it as a raft. The Styrofoam has dimensions 2.00 m X 2.00 m X 0.0900 m. The bottom 0.024 m of the raft is submerged. a) Draw a free-body diagram of the system consisting of the...
35. ### Need Help with a Basic Fluids Problem - Buoyancy and Archimedes' principle

Good afternoon, I am having some trouble solving this basic fluids problem, and I am hoping you can look over my work, and offer some assistance. Homework Statement A submarine has a total mass of 2.1 multiplied by 10^6 kg, including crew and equipment. The vessel consists of two parts...
36. ### Help with Archimedes' Principle

Homework Statement A solid aluminum sphere has a radius of 1.84 m and a temperature of 77.5 °C. The sphere is then completely immersed in a pool of water whose temperature is 26.7 °C. The sphere cools, while the water temperature remains nearly at 26.7 °C, because the pool is very large. The...
37. ### I have a couple of questions on archimedes' principle

the question is: consider that a balloon filled with 1 liter of water (1000 cm^3) in equilibrium in a container of water, what is the mass of the liter of water? what is the weight of the 1 liter of water? what is the weight of water displaced by the balloon ? what is the bouyant force on...
38. ### Archimedes' Principle- Popping lid off of a barrel

Homework Statement A barrel with diameter 80cm is completely full of water and sealed except for a piece of tube extending vertically through the lid with a diameter of 0.8cm. It's asking what height would you have to fill the small tube with in order to make the lid of the barrel pop off. The...
39. ### How Does Archimedes' Principle Apply to Forces on a Submerged Cube?

Homework Statement In the figure below, a cube of edge length L = 0.500 m and mass 480 kg is suspended by a rope in an open tank of liquid of density 1030 kg/m3. (a) Find Ftop, the magnitude of the total downward force on the top of the cube from the liquid and the atmosphere, assuming...
40. ### Calculating the Mass of a Piece of Glass Using Archimedes' Principle

1.a piece of metal of weight 20gms has equal apparent weight with a piece of glass when both are suspended from the arms of a balance and immersed in water(density 1).if water is replaced by alcohol(density 0.96), 0.84gms must be added to the pan from which the metal is suspended to restore...
41. ### Archimedes' Principle - Submerged object in a fluid

Homework Statement A 1.25kg wooden block has an iron ball glued to one side. (a) if the blocks floats in water with the iron ball "high and dry," what is the volume of wood that is submerged? (b) If the block is now inverted, so that the iron ball is completely immersed, does the volume of...
42. ### Exploring Archimedes' Principle: Real Data & Results

Does anyone have any real scientific/experimental data to prove whether Archimedes' principle should be taken literally? Let me explain: As I remember, Archimedes' principle goes something like upthrust is equal to the weight of the displaced fluid. Archimedes was saying that the force down...
43. ### Bridges and Archimedes' principle

I was reading some of my physics chapter and cam across an interesting question, which I am sure someon here can answer. It just interested me, so here it is. A barge filled high with sand approaches a low bridge over the river and cannot quite pass under it. Should sand be added to, or...
44. ### Buoyancy and Archimedes' Principle (helium ballon carrying cargo), HELP

I can not figure this out for the life of me! I know the answer is 920 kg, but I have to know how to get there so I can do my WebAssign problem! Here's the problem: " A spherical balloon has a radius of 7.35 m and is filled with helium. How large a cargo can it lift, assuming that the skin and...
45. ### What is the average density of the duck floating on a lake?

Probably an easy question, just can not figure it out. A duck is floating on a lake with 25% of its volume beneath the water. What is the average density of the duck? To me it seems like they do not provide enough information to figure the problem out, I am soo stuck.
46. ### Buoyancy and Archimedes' Principle

If an object floats in water, its density can be determined by tying a sinker on it so that both the object and sinker are submerged. Show that the specific gravity, (Density_substance)/(density_water at 4 degrees), is given by (w)/(w_1 - w_2), where w is the object's weight in air alone, w_1 is...
47. ### Finding Tension in a Submerged Ball Using Archimedes' Principle

A ball of mass m_b and volume V is lowered on a string into a fluid of density p_f . Assume that the object would sink to the bottom if it were not supported by the string. What is the tension T in the string when the ball is fully submerged but not touching the bottom? Express your answer (T)...
48. ### Calculating Volume Using Archimedes' Principle

An object is solid throuhgout. When the object is completely submerged in ethyl alcohol, its apparent weight is 15.2N. When completely submerged in water, its apparent weight is 13.7N. What is the volume of the object? This is my attempt: Weight of object in ethyl alcohol [Woe]= (density...