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प्रश्न
State the principle of floatation.
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उत्तर
“When a solid is floating in a fluid, the weight of whole solid acting vertically downward at its "Centre of Gravity", is equal to the weight of the fluid displaced by the "Immersed" part of solid acting upward, at its "centre of Buoyancy" or at the centre of the "Bulk of liquid" displaced.”
OR
“The weight of a floating body is equal to the weight of the liquid displaced by its "Submerged" part.”
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संबंधित प्रश्न
A body of volume V and density ρs , floats with volume v inside a liquid of density ρL. Show that `"v"/V = ρ_s/ρ_L` .
A weather forecasting plastic balloon of volume 15 m3 contains hydrogen of density 0.09 kg m-3. The volume of equipment carried by the balloon is negligible compared to its own volume. The mass of an empty balloon alone is 7.15 kg. The balloon is floating in air of density of 1.3 kg m-3. Calculate:
(i) The mass of hydrogen in the balloon,
(ii) The mass of hydrogen and balloon,
(iii) The total mass of hydrogen, balloon and equipment if the mass of equipment is x kg,
(iv) The mass of air displaced by balloon and
(v) The mass of equipment using the law of floatation.
A test tube loaded with lead shots, weighs 150 gf and floats upto the mark X in water. The test tube is then made to float in alcohol. It is found that 27 gf of lead shots have to be removed, so as to float it to level X. Find R.D. of alcohol.
A rubber ball floats in water with 2/7 of its volume above the surface of the water. Calculate the average relative density of the rubber ball.
A block of wood of volume 25 cm3 floats in water with 20 cm3 of its volume immersed in water.
Calculate:
(1) density of wood
(2) the weight of block of wood.
Name an instrument based on this principle. State two uses of the instrument that you describe.
Explain the following:
An egg sinks in fresh water but floats in a strong solution of salt.
Hydrometer is based on the principle of ______.
Where do we use lactometers?
