Tag: physics

Questions Related to physics

The specific gravity of ice is $0.9$. The area of the smallest slab of ice of height $0.5\ m$ floating in fresh water that will just support a $100\ kg$ man is

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

  1. $1.5\ m^{2}$

  2. $2\ m^{2}$

  3. $3\ m^{2}$

  4. $4\ m^{2}$

Show answer
Correct Option: B
Explanation:

wt. of man = 1000 N

wt. of ice = $0.9\times area\times 0.5N$
wt. of water = $1\times area\times 0.5N$
So, wt. of water = wt. of ice + wt. of man
      area $\times 0.5=area\times 0.9\times 0.5+2000$
      1 area = 20000 = ${ 2m }^{ 2 }$

A block of ice with a lead shot embedded in It is floating on water contained in a vessel. The temperature of the system is maintained at $0^{\circ}$ C as the ice melts. When the ice melts completely the level of water in the vessel rises.

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

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

According to Archemedies principle if any object is floating on a liquid the weight of the liquid displaced is equal to the weight of the object, when the block of ice melts the bullet ultimately sink in water and displaces the same volume of water as its own volume was, but when it was embedded in the ice it displaced move volume, therefore level of water will fall.

A rectangular boat floating in water has length 4 m and breadth 1.5 m. A person gets into the boat as a result of w which the boat sinks by 2 cm. Mass of the person is :

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

  1. 80 kg

  2. 100 kg

  3. 120 kg

  4. 92 kg

Show answer
Correct Option: C
Explanation:

Given,

$l=4m$
$b=1.5m$
$h=2cm=0.02m$
Volume, $V=lbh$
$V=4\times 1.5\times 0.02 =0.12m^3$
Density of water, $\rho=1000 kg/m^3$
Mass of the person, $M=\rho V$
$M=1000\times 0.12$
$M=120kg$
The correct option is C.

When a body is weighed in a liquid, the loss in its weight depends upon:

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

  1. volume of the body

  2. mass of the body

  3. shape of the body

  4. CG of the body

Show answer
Correct Option: A
Explanation:

Loss in weight is dependent on volume of body.

$ \therefore$ Option $A$ is correct.

FIll in the blank. 

When a solid floats in a liquid,  the weight of _______ by its immersed part of the solid is equal to the weight of the solid. 

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

  1. less

  2. buoyant force

  3. weight

  4. liquid displaced

Show answer
Correct Option: D
Explanation:

Liquid displaced.
This is known as Archimedes principle.
Archimedes' principle indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.

Archimedes' major contribution / discovery was:

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

  1. Photoelectric effect

  2. Principle of buoyancy

  3. Wave theory of light

  4. Law of inertia

Show answer
Correct Option: B
Explanation:

Answer is B

Archimedes' principle indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. Because of this buoyancy a body is able to float or submerge over liquid surface.

An iron ball is weighed in air and then in water by a spring balance

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

  1. Its weight in air is more than in water

  2. Its weight in water is more than in air

  3. Its weight in same both in air and water

  4. Its weight is zero in water

Show answer
Correct Option: A
Explanation:

By Archimedes Principle, an object immersed(partially or fully) in a fluid experiences a loss in weight, which is given by the weight of the fluid displaced by the body.


For the given iron ball, the weight measured in air is $W _1 = (m _\textrm{ball}-\rho _\textrm{air}V _\textrm{ball})g$
Similarly, weight measured in water is $W _2 = (m _\textrm{ball}-\rho _\textrm{water}V _\textrm{ball})g$

We know that, $\rho _\textrm{water} > \rho _\textrm{air}$
Hence, $W _2 <W _1$
i.e., Weight measured in air is more than that in water.

A cylinder is made up of a material of density $1.5\ g\ cm^{-3}$ is immersed inside a liquid of density $1\ g\ cm^{-3}$. State whether the cylinder moves up or not

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

  1. Yes

  2. No

  3. Maybe

  4. Can't say

Show answer
Correct Option: B
Explanation:

Let the volume of cylinder be V

So weight of cylinder is $W=V\rho _{cylinder}g=1.5Vg$
Buoyancy force $F=V\rho _{liquid}g=V\times 1\times g=Vg$
Since weight is greater than buoyancy, $W>F$, so it will move downward.

$A$ and $B$ are two metallic pieces. They are fully immersed in water and then weighed. Now they show same loss of weight. The conclusion therefore is:

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

  1. $A$ and $B$ have same weight in air

  2. $A$ and $B$ have equal volumes

  3. The densities of the materials of $A$ and $B$ are the same

  4. $A$ and $B$ are immersed to the same depth inside water.

Show answer
Correct Option: B
Explanation:

Same loss of weight implies equal buoyant forces on the object which is equal to weight of liquid displaced i.e. both the bodies have equal volumes.

Two solids A and B Float is a liquid. It is observed that A floats with half its volume immersed and B floats with $2/3$ of its volume immersed. Compare the densities of A and B.

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

  1. $4:3$

  2. $2:3$

  3. $3:4$

  4. $1:3$

Show answer
Correct Option: C
Explanation:

$\dfrac { density\quad of\quad A }{ density\quad of\quad B } =\dfrac { density\quad of\quad immersed }{ Volume\quad of\quad B\quad immersed } =\dfrac { 1/2 }{ 2/3 } $

$\dfrac { density\quad of\quad A }{ density\quad of\quad B } =\dfrac { 3 }{ 4 } $