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प्रश्न
It is easier to lift a heavy stone under water than in air. Explain.
उत्तर १
It is easier to lift a heavy stone under water than in air because in water, it experiences an upward buoyant force which balances the actual weight of the stone acting downwards. Thus, due to upthrust there is an apparent loss in the weight of the heavy stone, which makes it lighter in water, and hence easy to lift.
उत्तर २
It is easier to lift a heavy stone under water because in water an upthrust acts on the upward direction which reduces the apparent weight of the stone and makes it easy to lift.
संबंधित प्रश्न
Define the term Density of a substance.
The density of water is 1.0 g Cm-3. The density of iron is 7.8 × 10″3 g Cm-3. The density of mercury is 13.6 g Cm-3.
Ans the following:
Will a piece of iron float or sink in water?
Why does it happen?
A ship dips to a larger depth in fresh water as compared to marine water.
What do you understand by the term upthrust of a fluid? Describe an experiment to show its existence.
A body weighs 450 gf in air and 310 gf when completely immersed in water. Find
(i) The volume of the body,
(ii) The loss in weight of the body, and
(iii) The upthrust on the body.
State the assumption made in part (i).
Two spheres A and B, each of volume 100 cm3 is placed on water (density = 1.0 g cm-3). The sphere A is made of wood of density 0.3 g cm-3 and sphere B is made of iron of density 8.9 g cm-3.
- Find:
- The weight of each sphere, and
- The upthrust on each sphere.
- Which sphere will float? Give reason.
A balloon filled with helium gas floats in a big closed jar which is connected to an evacuating pump. What will be your observation, if air from the jar is pumped out? Explain your answer.
Select the correct option.
Unit of thrust in the SI system is
In a fluid, buoyant force exists because the pressure at the ______ of an object is greater than the pressure at the top.
Salt water provides less buoyant force than freshwater.
