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प्रश्न
Why is a force needed to keep a block of wood inside water?
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उत्तर
A force is required to hold a block of wood in water because the upthrust caused by water on the block when fully submerged surpasses its weight.
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संबंधित प्रश्न
State whether the following statement is true or false :
The buoyant force depends on the nature of object immersed in the liquid
How does the pressure exerted by thrust depend on the area of surface on which it acts? Explain with a suitable example.
Deduce an expression for the pressure at depth inside a liquid.
How does the liquid pressure on a diver change if :
The diver moves horizontally?
A hammer exerts a force of 1.5 N on each of the two nails A and B. The area of cross section of tip of nail A is 2 mm2 while that of nail B is 6 mm2. Calculate pressure on each nail in pascal.
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.
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.
Will a body weigh more in air or vacuum when weighed with a spring balance? Give a reason for your answer.
Figure shows the same block of wood floating in three different liquids A, B and C of densities ρ1, ρ2 and ρ3 respectively. Which of the liquid has the highest density? Give a reason for your answer.
Pressure in a water pipe on the ground floor of a building is 100,000 Pa. Calculate the pressure in the water pipe on the first floor at a height of 3 m. [Density of water = 1000 kgm−3 ; g = 10 ms−2]
