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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
Why do we feel light on our feet when standing in a swimming pool with water up to our armpits ?
When does an object float or sink when placed on the surface of a liquid ?
The density of brass is 8.4 g cm-3. What do you mean by this statement?
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A block of iron of mass 7.5 kg and of dimensions 12 cm × 8 cm × 10 cm is kept on a table top on its base of side 12 cm × 8 cm.
Calculate:
- Thrust and
- Pressure exerted on the table top
Take 1 kgf = 10 N.
(i) The diameter of neck and bottom of a bottle are 2 cm and 10 cm, respectively. The bottle is completely filled with oil. If the cork in the neck is pressed in with a force of 1.2 kgf, what force is exerted on the bottom of the bottle?
(ii) Name the law/principle you have used to find the force in part (a).
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Mass = .................... × density
What is meant by up thrust?
Assertion (A): The buoyant force on a submerged rigid object can be considered to be acting at the center of mass of the object.
Reason (R): In rigid body, force distributed uniformly through its volume can be considered to be acting at the centre of mass of the body.
Complete the analogy.
Downward force : Weight :: Upward force offered by liquid : _____.
