Tag: upthrust in fluids, archimedes' principle and floatation

Questions Related to upthrust in fluids, archimedes' principle and floatation

A solid sphere weighs $40 N$ in water and $45 N$ in a liquid of relative density $0.7$5 when completely immersed. The weight of sphere in air will be 

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. $50N$

  2. $53N$

  3. $80N$

  4. $60N$

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Correct Option: A

An ice block contains a glass ball when the ice melts within the water containing vessel, the level of water

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. Rises

  2. Falls

  3. Unchanged

  4. First rises and then falls

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Correct Option: B

A body is floating in liquid with  $50\%$  of its volume out side the liquid. When the entire system accelerates upwards with an acceleration  $g / 3 ,$  the percentage of its volume outside the liquid is

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. $33 \%$

  2. $50 \%$

  3. $25 \%$

  4. $66 \%$

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Correct Option: C

Ice pieces are floating in a beaker A containing water and also in a beaker B containing miscible liquid of specific gravity 1.2 When ice melts,the level of

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. Water increases in A

  2. Water decreases in A

  3. Liquid in B decreases

  4. Liquid in B increases

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Correct Option: C

A body floats in a liquid if the buoyant force is

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. zero

  2. less than its weight

  3. equal to its weight

  4. none of these

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Correct Option: B

A block of wood floats in water with (2/3)rd its volume submerged. The density of wood is 

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. ${ 67gm/cm^{ 3 } }$

  2. ${ 6.7gm/cm^{ 3 } }$

  3. ${0. 67gm/cm^{ 3 } }$

  4. $7\times { 10 }^{ 3 }kg/{ m }^{ 3 }$

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Correct Option: C

Initially A cubical block of density  $\rho$  is floating in water. in a vessel Out of its height  $L ,$  length  $x$  is submerged in water. Suddenly vessel is kept in an elevator accelerating upwards with acceleration  $a.$   What is the length immersed in water?

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. $L - X$

  2. $2 x$

  3. $x$

  4. $L$

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Correct Option: C

A ball falls through a liquid at a constant speed. It is acted upon by three forces: an upthrust, a drag-force and its weight.
Which statement is correct?

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. The drag-force increases with increasing depth

  2. The drag-force is equal to the sum of the upthrust and weight

  3. The upthrust is constant with increasing depth

  4. The weight is greater than the sum of the drag-force and the upthrust

Show answer
Correct Option: C
Explanation:

A ball falls through a liquid at a constant speed .

It acted upon by the three force ,
1. up thrust : it is constant
2. drag force
3, weight ; it is downward
Hence, C is correct option.

A cube of wood supporting $200g$ mass just floats in water. When the mass is removed, the cube rises by $1cm$, the linear dimension of cube is:

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. $10cm$

  2. $20cm$

  3. $10\sqrt{2}cm$

  4. $5\sqrt{2}cm$

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Correct Option: C
Explanation:

cube of wood supports$=200gm$
As, the mass is removed it rises by $1cm$
So, this implies that the weight of the $200g$ mass is equal to the weight of the water displaced by immersing $1cm$ of the cube,

Mathematically,
$a _{2}\times 1\times 1gm/cm^{3}\times g=g\times 200$
$a^{2}=10\sqrt{2}200cm^{2}$
$a=10\sqrt{2}cm$

A boat having a length of 3 metre and breadth 2 metre is floating on a lake. The boat sinks by one cm when a man gets on it. The mass of the man is:

physics upthrust in fluids, archimedes' principle and floatation upthrust is equal to the weight of displaced liquid pressure in fluids buoyancy

  1. 60 kg

  2. 62 kg

  3. 72 kg

  4. 128 kg

Show answer
Correct Option: A
Explanation:

Amount of water displaced is $V=3\times 2\times 0.01=0.06m^3$
$\therefore F=1000\times 0.06 \times g=60g$
hence the man weighs 60kgs