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1 . A U-tube contains liquid of unknown density. An oil of density 750 kg/m is p

ID: 1289269 • Letter: 1

Question

1. A U-tube contains liquid of unknown density. An oil of density 750 kg/m is poured into one arm of the tube until the oil column is 14.5 cm high. The oil-air interface is then 8.0 cm above the liquid level in the other arm of the U-tube. Find the density of the liquid.
kg/m

2. A helium balloon can just lift a load of 700 N. The skin of the balloon has a mass of 1.20 kg. What is the volume of the balloon?(the density of air is 1.29 kg/m and the density of helium is 0.179 kg/m)
m

1. A U-tube contains liquid of unknown density. An oil of density 750 kg/m is poured into one arm of the tube until the oil column is 14.5 cm high. The oil-air interface is then 8.0 cm above the liquid level in the other arm of the U-tube. Find the density of the liquid. kg/m 2. A helium balloon can just lift a load of 700 N. The skin of the balloon has a mass of 1.20 kg. What is the volume of the balloon?(the density of air is 1.29 kg/m and the density of helium is 0.179 kg/m) m

Explanation / Answer

Q-1 Pressure on each side of the tube are same.

?gh = ? ' g h '

?h = ? ' h '     ---( 1)

From problem , density of oil ? = 750 kg / m ^ 3

                          height h = 14.5 cm

                   height of the column in liquid side h ' = 8 cm

from eq ( 1 ) density of liquid ? ' = ?h/ h '

                                              = 750*14.5 / 8

                                             = 1359.4 kg / m ^ 3 --> Answer to Q-1)

Q-2)

Weight of balloon + weight of load + weight of helium = weight of air displaced.

1.2 * 9.80   + 700   + density of helium * volume * g  = density of air * volume * g

711.76 +    0.179 * V * 9.80   = 1.29 * V *9.80

711.76 +    1.7542 V =   12.642 V

711.76 =   10.8878 V

V =    65.4 m3 --> Answer to Q-2)