Tag: upthrust in fluids, archimedes' principle and floatation

Quizzes (4) Questions (190)

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

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

A ball weighing  $4 kg$  of density  $4000{ kg }\quad { m }^{ { -3 } }$  is completely immersed in water of density  $1000{ kg }\quad { m }^{ { -3 } }.$  Find the force of buoyancy on it. (Given $g = 10 { ms } ^ { - 2 }$)

  1. $100{ N }$
  2. $1{ N }$
  3. $20{ N }$
  4. $10{ N }$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Buoyant force is equal to the weight of the displaced liquid. Volume of the ball = mass / density = 4kg / 4000kg/m^3 = 0.001 m^3. Buoyant force = volume * density_water * g = 0.001 * 1000 * 10 = 10 N.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

A balloon has volume of $1500\, m^3$. It is filled with hydrogen $(\rho = 0.09\, gL^{-1})$. If the density of air is $1.29\, gL^{-1}$, it can lift a total weight of 

  1. $2400\, kg$
  2. $1600\, kg$
  3. $2700\, kg$
  4. $1800\, kg$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The net upward force (lift) is equal to the difference in weight between the displaced air and the hydrogen gas inside the balloon. Lift = V * (rho_air - rho_hydrogen) = 1500 * (1.29 - 0.09) g/L = 1500 * 1.20 g/L = 1800 kg.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

An object measuring $2\times 2\times 5{cm}^{3}$ has a mass of $16g$. It is put in water of density $1g/cc$. Percentage of its volume outside water while floating is

  1. $10$%
  2. $20$%
  3. $30$%
  4. $40$%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The volume of the object is 2 * 2 * 5 = 20 cm^3, and its mass is 16 g, giving a density of 16/20 = 0.8 g/cc. The fraction of volume submerged is equal to the relative density (0.8/1.0 = 0.8 or 80%), which means the percentage of volume outside water is 100% - 80% = 20%.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

lce 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

  1. Water increases in $A$
  2. Water decreases in $A$
  3. Liquid in $B$ decreases
  4. Liquid in $B$ increases
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When ice melts in water, the level remains unchanged because the weight of the displaced water equals the weight of the ice. In a liquid with specific gravity > 1, the ice displaces a smaller volume of liquid than its own melted volume, so the level decreases.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

Statement I:- An ice ball is floating in water. Some stone pieces are embedded inside the ice. When ice will melt level of water will fall.
Statement I:- In floating condition,stone pieces will displace more liquid compared to the condition when they sink.

  1. Statement I is true,statement II is true and statement II is a correct explanation for statement I.

  2. Statement I is true,statement II is true and statement II is NOT the correct explanation for statement I.

  3. Statement I is true,Statement II is false.

  4. Statement I is false,Statement II is true.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When ice with embedded stones melts, the stones sink. While floating, the stones displace liquid equal to their weight (due to the ice). Once they sink, they only displace their own volume, which is less than the volume of liquid required to support their weight.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

A block of wood is floating in water in a closed vessel as shown in the figure. The vessel is connected to an air pump. When more air is pushed into the vessel, the block of wood floats with : (neglect compressibility of water)

  1. Larger part in the water

  2. Smaller part in the water

  3. Same part in the water

  4. At some instant it will sink
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The buoyant force depends on the weight of the displaced fluid. Since the block is floating, the buoyant force equals the weight of the block. Increasing air pressure does not change the density of the water or the weight of the block, so the submerged volume remains the same.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

A block of wood floats is water with $ 2/5^{th} $ of its volume above the surface Calculate the density of wood.

  1. $ 0.6 g/cm^3 $
  2. $ 1.6 g/cm^3 $
  3. $ 2.5 g/cm^3 $
  4. $ 3.6 g / cm^3 $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since 2/5th of the volume is above the surface, 3/5th of the volume must be immersed in water. The density of the wood is therefore 3/5 (or 60%) of the density of water, which equals 0.6 g/cm^3.

Multiple choice physics upthrust in fluids, archimedes' principle and floatation applications of floatation principle of floatation and its applications when do objects float on water?

We have two different liquids A and B whose relative densities are 0.75 and 1.0, respectively. If we dip solid objects P and Q having relative densities 0.6 and 0.9 in these liquids, then:

  1. P floats in A and Q sinks in B

  2. P sinks in A and Q floats in B

  3. P floats in B and Q sinks in A

  4. P sinks in B and Q floats in A
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If solid object has higher density than liquid then it will sink in that liquid otherwise it will float.
R.D. of liquid A = 0.75
R.D. of liquid B = 1.0
R.D. of object P = 0.6
R.D. of object Q = 0.9

  • P has R.D. less then both the liquids. so it will float in both the liquids.
  • Q has R.D. more than liquid A, so it will sink in A.
  • Q has R.D. less than liquid B, so it will float in B.