Archimedes' principle states that the buoyant force on an object submerged or partially submerged in a fluid is equal to the weight of the fluid the object displaces. This principle can be used to calculate density and relative density. It also explains why ships and submarines float or sink depending on whether the object's density is greater than, equal to, or less than the fluid it is placed in. Applications of Archimedes' principle include ship building, submarine operations, and how certain aquatic animals and balloons are able to achieve buoyancy.

1. ARCHIMEDES’PRINCIPLE

2. DENSITY- Density of a substance is defined as the mass per unit volume of that substance

3. Its S.I Unit is kg/meter cubeFUNDAMENTALS

4. Density formula Units of Density can be found usingDensity = Mass m Volume v Units g/ml, g/cm3, g/cc Remember 1 ml = 1 cm3 = 1 cc

5. RELATIVE DENSITY- The Relative Density is the ratio of density of substance to the density of water at 4 C

6. Since it is a ratio it has no unit

7. It is also called specific gravityShortcut formulaIf the density of a substance is 3.6 gm/cm cube, its RELATIVE DENSITY is 3.6 Because RELATIVE DENSITY of a substance is equal to its density(with no unit).This is the relation between density and relative density Conversely if RELATIVE DENSITY is 1.4,its density is 1.4gm/cm cube

8. We know that density of water is 1gm/cm ccRELATIVE DENSITY of a substanceBut how to prove this?Density of substance=Density of water at 4CDensity of substance=1gm/cm cubeDensity of substance=

9. Interesting factArchimedes' Principle is named after “ARCHIMEDE’S OF SYRACUSE "who first discovered this law

10. Archimedes’ PrincipleArchimedes Principle states that when a body is partially or completely immersed in a fluid, it experiences an apparent loss in weight due to upthrustand this apparent loss in weight is equal to the weight of the fluid displaced by the immersed part of the bodyUpthrust means Buoyant force

11. What is BUOYANCY and UPTHRUST?What is BUOYANCY and UPTHRUST?Or upthrust

12. BOUYANT FORCE or UPTHRUSTWhen a body is immersed partially or completely inside a fluid it experiences an upward force called the buoyant force

13. Buoyancy The property of the fluids to apply buoyant force is called BUOYANCY

14. The buoyant force acting on an object depends upon two factors:The volume of the body immersed i.e. volume of the fluid displaced ,or

15. density of the fluidApparent loss in weight= True weight-weight of the body immersed in a fluid (=buoyant force)= w1-w2

16. Buoyant force=apparent loss in weight-true weight(w1)

17. Materials required for verifying Archimedes principle are:Verify Archimedes principleSPRING BALANCESTONEEUREKA CANBEAKER

18. Verifying Archimedes’ principleTake an Eureka can and fill it up to its spout. Take a stone and suspend it with the hook of the spring balance.Note the weight of stone in air.Let it be w1.Now immerse the stone inside water in the Eureka can.the water overflows through the can.Collect this overflowing water in the beaker. Now also note the reading in the spring balance.Let it be w2

19. This w2 will be less than w1 due to upthrust provided by water.Apparent loss in weight due to upthrust will be (w1-w2)Measure the weight of water collected in the beaker , which in fact is the weight of water displaced by the stone .On comparing we will found that the loss in weight (w1-w2 )is equal to the weight of the water displaced by the stone.Hence the Archimedes’principle is verified.It states that when a body is partially or completely immersed in a fluid, it experiences an apparent loss in weight due to upthrust and thisapparent loss in weight is equal to the weight of the fluid displaced by the immersed part of the body

21. Principle of FloatationA body floats in a liquid if the weight of the body is equal to the weight of the liquid displaced by it

22. Sinking AND FLOATATION OF A BODYWhen a body is placed in a liquid, two forces act on itThe following are the three possibilities if we consider w1 and w2:

26. Where will they “float?”Object A: density= 0.8 g/ccObject B:density= 0.95 g/ccObject C:density= 1.1 g/ccoildensity= 0.9 g/ccObject D:density= 1.3 g/ccObject E:density= 4.0 g/ccfresh waterdensity= 1.0 g/ccsalt waterdensity= 1.2 g/cc

27. Applications of Archimedes’ principleShips and submarines are designed on the basis of this principle

28. How does a steel ship floats ?

29. A ship is hollow at the bottom because of which its average density is lees than that of water so the ship is able to displace water equal to its weight and hence it floats.

30. How can a submarines float or submerge in water?

31. Submarines have ballast tanks at its basement. When it is to be submerged,these tanks are filled with sea water.As a result its weight becomes more than the weight of water displaced.So it submerges

32. If the submarine has to come up,the tanks are emptied out ,so the weight of the submarine decreases in comparison to the weight of the water displaced and the submarine rises up to the surface

33. The fishesSome species of fishes have swim bladder. When fishes want to rise they fill this bladder with gases diffused from their own body. Thus becoming lighter and to go down they empty their bladder thereby increasing their density and hence manage to sink

35. Hydrogen and Helium filled balloons and hot air balloons tend to move upwards because the density of hydrogen is about 1/4th of the air. The upward force is more than the downward force of the balloon and hence it rises upwards till the density of both becomes same