Physics
Assertion (A) : In order to come to surface of water, whales fill their swim bladder with water.
Reason (R) : A body floats when the density of the body is less than the density of the liquid.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Measurements
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Answer
Assertion is false but reason is true
Explanation
Assertion (A) is false because in order to come to the surface of water, whales fill the bladder with air to decreases the average density of the whale and so it rises to the surface.
Reason (R) is true because a body of density greater than the density of liquid, sinks inside the liquid, while a body of density equal or less than the density of liquid, floats on the liquid.
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Related Questions
A piece of wood floats on water. The buoyant force on wood will be:
- zero
- more than the weight of the wood piece.
- equal to the weight of the wood piece.
- less than the weight of the wood piece.
The weight of a body is more than the buoyant force experienced by it, due to a liquid. The body will:
- sink
- float with its some part outside the liquid.
- float just below the surface of liquid.
- float with whole of its volume above the surface of liquid.
Fill in the blanks:
(a) 1 kg is the mass of …………… mL of water at 4°C.
(b) Mass = density x …………… .
(c) The S.I. unit of density is …………… .
(d) Density of water is …………… kg m-3.
(e) 1 g cm-3 = …………… kg m-3.
(f) The density of a body which sinks in water is …………… than 1000 kg m-3.
(g) A body sinks in a liquid A, but floats in a liquid B. The density of liquid A is …………… than the density of liquid B.
(h) A body X sinks in water, but a body Y floats on water. The density of the body X is …………… than the density of body Y.
(i) The buoyant force experienced by a body when floating in salt-water is …………… that when floating in pure water.
(j) The weight of a body floating in a liquid is …………… .
Write true or false for each statement:
(a) Equal volumes of two different substances have equal masses.
(b) The density of a piece of brass will change by changing its size or shape.
(c) The density of a liquid decreases with increase in its temperature.
(d) Relative density of water is 1.0.
(e) Relative density of a substance is expressed in g cm-3.
(f) When a body is immersed in a liquid, the buoyant force experienced by the body is equal to the volume of the liquid displaced by it.
(g) If a body floats in different liquids, different volumes of the body get submerged in different liquids, but in each liquid the weight of the liquid displaced by the submerged part of body remain the same.
(h) A body experiences the same buoyant force when it floats or sinks in water.
(i) A body floats in a liquid when its weight becomes equal to the weight of the liquid displaced by its submerged part.
(j) A body while floating, sinks deeper in a liquid of low density than in a liquid of high density.