8/6/2019 LAB 4 Archimedes Principle pract mine

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Emily Ha 1

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LAB 4 Archimedes Principle

i) Group Members: Thanh Minh Le, Emily Ha

ii) Aim: To examine Archimedes Principle in a body that is partially or totally immersedin fluid, that the buoyancy force on an object is equal to the weight of the fluid displaced

by the object. That is, its apparent l oss in weight (buoyant force, B) is equal to theweight of the fluid displaced by the body.

Part A

iii) Method (a) :

1. Using a top-pan balance, determine the mass of the Aluminium (M Al) and woodblock (Mw).

2. Using a ruler, determine the volumes of the aluminium and wood blocks.3. Calculate densities of aluminium and wood fro m their respective masses and

volumes using the formula m= v.

Method (b):

4. Using the spring-balance , measure the apparent weight of the aluminium in airWAl and measure when the aluminium is immersed in water.

5. Calculate the apparent loss in weight of the aluminium given by WAl W.6. Calculate the volume of water displaced as equivalent to the volume of

aluminium as it is completely immersed in water (Archimedes Principle) usingdensity of water 1.00 x 103 kg/m3.

7. Place the wood in a large container of water. Mark its height above the surfaceon the water to be hand height of the block being H.

8. In accordance to Archimedes Principle, calculate the density of the wood floatingin water.

Part B

9. Fill a 100cc beaker approximately two-thirds full of water and r ecord its masson a top-pan balance. Calculate its weight W1.

10.Suspend the aluminium in water until it is completely immersed. Record it as W 2.11.Determine the weight change (W2 W1) and compare this with (WAl W).

vi) Part C Problem Solution

i) Mass of oil displaced

ii) Density of oil

8/6/2019 LAB 4 Archimedes Principle pract mine

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vii) Conclusion

Method A in comparison to method B reveals more reliable measurements due to

decrease systematic and instrument error. Method B consumes more time to conduct aswell as involving procedures that induce instrument errors. E.g. use of the spring-balance will cause instrument error due to inaccuracy of the instrument. Also, floatingthe wood on water and measuring the height about the water is not exact either as theremay be human error in determining the horizontal level of the water that marks theblock. As this method requires the equation between density of wood, density of waterand the fraction of wood submerged, the inaccuracy of h and H will impact on theexperiments overall accuracy and reliability of results.

To find density, we need mass and volume. Method A proves to be more accurate butonly when the objects volume is easy to measure with a ruler. Method B can be used tomeasure objects that do not have symmetric or irregular shapes. The purpose of MethodB is based on Archimedes Principle to measure the irregular volume of a shape based

on measuring the volume of the displaced liquid once the object is submerged in water.

According to Archimedes Principle FB = wA wF, it is possible to determine the densityof the object without determining its volume by also applying the formula F= gV. W Al W gives us the apparent loss in weight of aluminium. Using Archimedes Principle tocalculate the volume of water displaced and the density of water (1.00 x 10 3 kg/m3) wecan obtain the volume of aluminium. In Part B of the experiment, we obtain W 1 and W2 . W1will be less than W2 due to the buoyancy provided by the water. Apparent loss in weightdue to the upthrust of the water is W2 W1. On comparison of WAl W and W2 W1, weconclude they are of equal value. That is the loss in weight of W 2 W1 is equal to theweight of the volume displaced by the aluminium given by W Al W. Hence, ArchimedesPrinciple holds true for this experimentation. It states that When an object is immersedin a fluid, there is an upwardbuoyant force equal to the weight of the volume of

fluiddisplaced by the object.