GOLDEN CROWN CRISIS…

EXPERIMENT

Aim: To find the relationship between the weight of water displaced and buoyant force.

Figure 1 : Arrangement of apparatus

Archimedes Principle• “When an object wholly or partially immersed in a fluid, it experiences an upward thrust equal to the weight of the fluid displaced.This net force exerted on the object by the fluid is called the buoyant force :

FB = P2 A – P1 A = (P2-P1) A = ρ g h A

Using that h A=V is the volume of the fluid andthat ρ V=m is the mass of the fluid one finds thatFB = weight of fluid displaced by the object

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

Also

FB= weight of displaced water

For a floating object: Wobject = Wdisplaced fluid

Archimedes Principle (summary)

• Buoyant Force (FB)Buoyant force = weight of fluid

displacedFB = ρfluid x Vdispl gW = Mg = ρobject Vobject gMg=ρVg

•If object floats….FB=W

Therefore ρfluid g Vdispl. = ρobject g VobjectTherefore Vdispl./Vobject = ρobject / ρfluid

Application of Archimedes’ Principle

• SubmarineSubmarine

Cross Section

QUESTIONS:-What Do you Think……..1) What will happen when

the ballast tanks are filled with air?

Why?

2)What will happen when the ballast tanks are filled with water?

Why?

When the tanks are full of air, the sub weighs less than the volume of water it displaces and it floats.

When the ballast tanks are flooded with water, the sub weighs more than the water it displaces, and it sinks.   

• HydrometerHydrometer

• Water Transport (Ship)Water Transport (Ship)

• Hot BalloonHot Balloon

Other applications of Other applications of Archimedes’ PrincipleArchimedes’ Principle

QUESTIONSQUESTIONS

1.1. State Archimedes’ Principle.State Archimedes’ Principle.

2.2. State two applications of Archimedes’ Principle.State two applications of Archimedes’ Principle.

3.3. Two metallic blocks being measured by a spring Two metallic blocks being measured by a spring balance. It is found that the balance shows a balance. It is found that the balance shows a reading of 7.2 N if measured in air and it shows a reading of 7.2 N if measured in air and it shows a reading of 6.4 N when measured in water.reading of 6.4 N when measured in water.Calculate theCalculate the(a)(a) loss in weightloss in weight(b)(b) weight of water displaced by the metallic weight of water displaced by the metallic blocks.blocks.(c)(c) upward thrust on the metallic blocks.upward thrust on the metallic blocks.