Tag: physics

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

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

  1. Rises

  2. Falls

  3. Unchanged

  4. First rises and then falls
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When the ice melts, the water level depends on the density of the object inside. Since the glass ball is denser than water, it displaces more water when it is part of the floating ice than it does when it sinks to the bottom after the ice melts, causing the level to fall.

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

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

  1. ${ 67gm/cm^{ 3 } }$
  2. ${ 6.7gm/cm^{ 3 } }$
  3. ${0. 67gm/cm^{ 3 } }$
  4. $7\times { 10 }^{ 3 }kg/{ m }^{ 3 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a floating object, the ratio of the submerged volume to the total volume is equal to the ratio of the density of the object to the density of the liquid. Here, 2/3 = rho_wood / rho_water. Since rho_water = 1 g/cm^3, rho_wood = 0.67 g/cm^3.

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

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?

  1. $L - X$
  2. $2 x$
  3. $x$
  4. $L$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The fraction of the block submerged is determined by the ratio of the density of the block to the density of the liquid. This ratio is independent of the acceleration of the system, as both the weight and the buoyant force are scaled by the same factor (g + a).

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

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?

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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:

  1. $10cm$
  2. $20cm$
  3. $10\sqrt{2}cm$
  4. $5\sqrt{2}cm$
Reveal answer Fill a bubble to check yourself
C Correct answer
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,
$a _{2}\times 1\times 1gm/cm^{3}\times g=g\times 200$
$a^{2}=10\sqrt{2}200cm^{2}$
$a=10\sqrt{2}cm$

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

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:

  1. 60 kg

  2. 62 kg

  3. 72 kg

  4. 128 kg
Reveal answer Fill a bubble to check yourself
A Correct answer
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