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प्रश्न
It is easier to lift a heavy stone under water than in air. Explain.
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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
State whether the following statement is true or false :
The buoyant force depends on the nature of object immersed in the liquid
What is the scientific name of the 'upward force' acting on an object immersed in a liquid?
An object of weight 200 N is floating in a liquid. What is the magnitude of buoyant force acting on it ?
Why does a block of wood held under water rise to the surface when released ?
What is meant by pressure? State its S.I. unit.
The area of base of a cylindrical vessel is 300 cm2. Water (density= 1000 kg m-3) is poured into it up to a depth of 6 cm. Calculate : (a) the pressure and (b) the thrust of water on the base. (g = 10m s-2.
The pressure of water on the ground floor is 40,000 Pa and on the first floor is 10,000 Pa. Find the height of the first floor. (Take : density of water = 1000 kg m-3, g = 10 m s-2)
Two cylindrical vessels fitted with pistons A and B of area of cross-section 8 cm2 and 320 cm2 respectively are joined at their bottom by a tube and they are completely filled with water. When a mass of 4 kg is placed on piston A, Find:
- the pressure on piston A,
- the pressure on piston B, and
- the thrust on piston B.
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.
Complete the analogy.
Downward force : Weight :: Upward force offered by liquid : ______
