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Questions Related to physics

A piece of paraffin wax of density 0.9 g/cc floats on water.A layer of turpentine of density 0.87 g/cc is added on top of water until the wax is entirely submerged.The ratio of the volume of wax immersed in water to that in turpentine is 

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. 3 : 13

  2. 87 : 90

  3. 90 : 87

  4. 3 : 10

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Correct Option: D
Explanation:

Buoyant force = weight of liquid displaced

hence $0.9V=1\times { V } _{ 1 }+0.87\times { V } _{ 2 }$
            & $V={ V } _{ 1 }+{ V } _{ 2 }$
               $0.9\left( { V } _{ 1 }+{ V } _{ 2 } \right) ={ V } _{ 1 }+0.87{ V } _{ 2 }$
               $0.9{ V } _{ 1 }+0.9{ V } _{ 2 }={ V } _{ 1 }+0.87{ V } _{ 2 }$
                        $\boxed { \dfrac { { V } _{ 1 } }{ { V } _{ 2 } } =\dfrac { 3 }{ 10 }  } $

The densities of objects P,Q,R and S are ${200 kg/m^3}$, ${450 kg/m^3}$, ${1200 kg/m^3}$  and ${785 kg/m^3}$ respectively. Which one of these objects will sink when dipped in a bucket of water?

physics forces in fluids experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. P

  2. Q

  3. R

  4. S

Show answer
Correct Option: C
Explanation:

Answer is C.

According to the laws of flotation, the more denser liquid will sink below and the less dense material will float.
In this case, the object R has the maximum density of $1200kg/{ m }^{ 3 }$.
Therefore, object R will sink when dipped in a bucket of water.

A 70 g substance has a volume of $35:cm^3$. It will float on the surface of the water.

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. True

  2. False

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Correct Option: B
Explanation:

Given:
Mass of substance $= 70g$.
Volume of substance $= 35cm^3$
density of water $= 1gm^{-3}$
By using the formula,
Density $=\dfrac{Mass}{Volume}$
Density of sub stance $= \dfrac{70}{35}=2gm^{-3}$
since, the density of the substance is more than the density, the gravitational force acting on it will be stronger than the buoyant force of water acting it, it will sink and not float on the surface of water

A piece of wood floats in water, completely inside it. What happens when it is dropped in ethanol?

physics forces in fluids experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. It floats higher

  2. Stays as before

  3. It sinks

  4. It sinks first and then rises

Show answer
Correct Option: C
Explanation:

Since , the ethanol is less denser than the water.Therefore, a piece of wood floating completely in water will sink in the ethanol.

As the density of a series of liquids increases, the upthrust on the iron rod submerged

physics forces in fluids experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. Increases

  2. Decreases

  3. Remains constant

  4. Noting can be said

Show answer
Correct Option: A
Explanation:

As the density of liquid increases & so does the buoyant force on the submerged rod which will result in increase in upthrust.

An object is placed in 3 beakers containing liquids A, B and C respectively. If the density of object (d) when compared to tensities of liquids A, B and C is given by $d _A < d < d _B < d _C$ then the body sinks in

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. liquid A

  2. liquid B

  3. liquid C

  4. all the three liquids

Show answer
Correct Option: A
Explanation:

When the density of the liquid is greater than that of object, then the weight of liquid displaced is greater than or equal to the weight of the object. This means that the buoyant force acting on the object is greater or equal to the weight of the object which makes the object to float in that liquid. 

Hence the object will float in liquids B and C as the densities of liquids B and C are more than that of the object while the object will sink in liquid A as the density of liquid A is less than that of the object.

A body of mass $120kg$ and density $600kg/{m}^{3}$ floats in water. What additional mass could be added to the body so that the body will just sink?

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. $20kg$

  2. $80kg$

  3. $100kg$

  4. $120kg$

Show answer
Correct Option: B
Explanation:

Weight of the water displaced= weight of body + additional mass

${ \rho  } _{ w }Vg=Mg$   ($M$ is the total mass)
${ \rho  } _{ w }V=M=\left( 100+m \right) \ V=\cfrac { 120 }{ 600 } =0.2{ m }^{ 3 }\ 1000\times 0.2=\left( 120+m \right) \ m=80kg$

Write the following steps in a sequence to verify Archimedes' principle.
(a) The object is completed immersed in a liquid.
(b) The weight of the object in air is measured by using a spring balance ($w _{1}$).
(c) The weight of the object in the given liquid is determined ($w _{1}$).
(d) The loss of weight of the object ($w _{1}-w _{2}$) is determined.
(e) The weight of the liquid displaced by the object (w) is determined.
(f) The value of ($w _{1}-w _{2}$) is compared with the value of (w).

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. b a c d e f

  2. a b d c f e

  3. a b c d e f

  4. f e c a b d

Show answer
Correct Option: A
Explanation:

Option (A) follows correct procedure as initially weight of the object is calculated in the air than it is immersed in liquid and its weight is measured in the liquid and then the diffrence between the two weights would be calculated  and than weight of liquid displaced by the body would be calculated and later the two diffrences would e compared.

so option (A) is correct.

The density of ice is $917\ kgm^{-3}$. What fraction of the volume of a piece of ice will be above water, when floating in fresh water?

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. 0.06

  2. 0.083

  3. 0.038

  4. 0.068

Show answer
Correct Option: C

Construction of a submarine is based on.

physics upthrust in fluids, archimedes' principle and floatation experimental verification of archimedes' principle archimedes' principle archimedes' principle and its applications

  1. Bernoulli's theorem

  2. Pascal's law

  3. Archimedes' principle

  4. None of these

Show answer
Correct Option: C
Explanation:

Construction of a submarine is based on Archimedes' principle.