upthrust-in-fluids-archimedes-principle-and-floatation

When a body is fully or partly immersed in a liquid, it undergoes an apparent loss in its weight due to:

• Decrease in its volume

• Decrease in the density of the body

• Upward thrust exerted by the liquid

• Decrease in its mass

A body weighs 200 gf in air and 175 gf when it is completely immersed in water. The buoyancy force acting on it is

• 25 gf

• 25 kgf

• 2.5 kgf

• 2.5 gf

A packet of 400 g and volume 200 cm³ is put in a water tank. The relative density of packet is

• 2

• 200

• 4

• 400

An object of mass 4 kg and density 2 x 10³ kgm^-3 is completely immeresed in water, its apparent weight will be

• 2 kgwt

• 20 kgwt

• 1 kgwt

• 10 kgwt

Relative density of a substance is expressed by comparing the density of that substance with the density of

• mercury

• air

• iron

• water

• water at 4^oC.

Calculate the mass of air in a room of dimensions 4.5 m X 3.5 m X 2.5 m if the density of air at N.T.P is 1.3 kgm^-3

• 51.19 kg

• 0.03 kg

• 31.29 kg

• 50 kg

A piece of wood of R.D. 0.25 floats in a pail containing oil of R.D., of 0.81. The fraction of volume of the wood above the surface of the oil is

• 0.31

• 0.69

• 0.21

• 0.79

A solid of mass 22 kg is immersed in water. If it looses half of its weight in water, its R.D. will be

• 1/2

• 1/4

• 4

• 2

The centre of gravity and the centre of buoyancy of a floating body in stable equilibrium

(i) are always same

(ii) are always along a same vertical line

• only (i) is true

• only (ii) is true

• Both (i) and (ii) are correct

• Both (i) and (ii) are false

A sample of milk diluted with water has a density of 1040 kgm^-3. If pure milk has a density of 1080 kgm^-3 then the percentage of water by volume in milk is:

• 40%

• 45%

• 50%

• 55%