Tag: concept of pressure

Questions Related to concept of pressure

1000 small balls each weighing 1 g strike one sq. cm of a area per second with a velocity of 100 m/sec in a normal direction and rebound with the same velocity. The pressure on the surface (in N/m$^2$) is :

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. $2 \times 10^3$

  2. $4 \times 10^6$

  3. $10^7$

  4. $2 \times 10^6$

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Correct Option: D

Identify the following shows the application of pressure in our everyday life?

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. The blade of Ice-skating shoe is very sharp.

  2. It is easier to drive a sharp tipped nail into wood.

  3. Sharp knife cuts better.

  4. Foundation of high-rise building are kept narrow.

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Correct Option: A,B,C,D
Explanation:

(A) if we decrease the area of the ice skating blades, then we mean to say we are increasing the pressure. We actually do this to increase pressure which reduces the chances of getting slipped.

(B) same concept is applicable in this as it was in the option (a). sharp tipped nail is having less area  and therefore exerts more pressure when it is tipped. so it easily gets tipped into the wood or even into the walls.
(C) same concept is in this option as well.
(D) same concept as it was in the previous 3 options. 

Choose the correct statement from the following?

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. Pressure is same at all points in the horizontal plane.

  2. A liquid seeks its own level.

  3. The lateral pressure exerted by a liquid decreases with the increase in depth of the liquid.

  4. The upper surface of a stationary liquid is always horizontal.

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Correct Option: A,B,D
Explanation:

(a) Pressure is same at all points in the horizontal plane. (correct)
(b) A liquid seeks its own level. (correct)
(c) The lateral pressure exerted by a liquid decreases with the increase in depth of the liquid. (wrong)
(d) The upper surface of a stationary liquid is always horizontal. (correct)

For the equlibrium AB (g) $\rightleftharpoons A (g) + B(g). K _p$ is equal to four times the total pressure. Calculate the number moles of A formed if one mol of AB is taken initially 

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. 0.45

  2. 0.30

  3. 0.60

  4. 0.90

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Correct Option: D

A same amount of same gas of temperature T are enclosed in a three identical vessel A,B, & C. The temperature of wall of three container is $T _A , T _B$ & $T _C (T _A > T _B > T _C)$ respectively. The pressure on wall of vessel. 

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. $P _A > P _B > P _C$

  2. $P _A < P _B < P _C$

  3. $P _A = P _B = P _C$

  4. Deta's are insufficient to decide.

Show answer
Correct Option: A
Explanation:

$\begin{array}{l} PV=nRT \ P\propto T \ \therefore \, { T _{ A } }>{ T _{ B } }>{ T _{ C } } \ So, \ { P _{ A } }>{ P _{ B } }>{ P _{ C } } \ Hence, \ option\, \, A\, \, iscorrect\, answer. \end{array}$

A hole is made at the bottom of a tank filled with water. If total pressure at the bottom of the tank is three atmosphere, then the velocity of efflux at the bottom is (1 atm = $10^5 N/m^2$)

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. $\sqrt{400} m/s$

  2. $\sqrt{200} m/s$

  3. $\sqrt{600} m/s$

  4. $\sqrt{500} m/s$

Show answer
Correct Option: A
Explanation:

Given,

$\begin{array}{l} P=1000kg/{ m^{ 3 } } \ P=3atm=3\times { 10^{ 5 } }N/{ m^{ 2 } } \ { P _{ 0 } }=1atm={ 10^{ 5 } }N/{ m^{ 2 } } \end{array}$
Pressure due to liquid column is 
$P - {P _0} =\rho gh$
velocity of flux $V = \sqrt {2gh} $
$\begin{array}{l} V=\sqrt { 2\dfrac { { \left( { p-{ P _{ 0 } } } \right)  } }{ \rho  }  }  \ =\sqrt { \dfrac { { 2\left( { 3\times { { 10 }^{ 5 } }-{ { 10 }^{ 5 } } } \right)  } }{ { 1000 } }  }  \ =\sqrt { \dfrac { { 4\times { { 10 }^{ 5 } } } }{ { 1000 } }  }  \ =\sqrt { 400 } m/s \end{array}$
Hence,
option $A$ is correct answer.

$3$ moles of a monoatomic gas requires $60\ cal$ heat for $5^{\circ}C$ rise of temperature at constant volume, then heat required for $5$ moles of same gas under constant pressure for $10^{\circ}C$ rise of temperature is $(R = 2\ cal/mole-k)$.

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. $200\ cal$

  2. $400\ cal$

  3. $100\ cal$

  4. $300\ cal$

Show answer
Correct Option: C

Temperature of $1\ mole$ of a gas is increased by $2^ {o}C$ at constant pressure, work done is

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. $R$

  2. $2R$

  3. $R/2$

  4. $3R$

Show answer
Correct Option: B
Explanation:

$W = nR\Delta T$

$ = 1\,molRJ\,{K^{ - 1}}\,mo{l^{ - 1}}\,2K$
$ = 2R\,\,joules$
Hence,
option $(B)$ is correct answer.

Air is pumped into an automobile tube upto a pressure of $200 \mathrm{kP}  $ in the morning when the air temperature is $  22^{\circ} \mathrm{C}  $ . During the day, temperature rises to $ 42^{\circ} \mathrm{C}  $ and the tube expands by $2 \%  $ . The pressure of the air in the tube at this temperature, will be approximately

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. $212 \mathrm{kPa} $

  2. $209 k P a $

  3. $206 \mathrm{kPa} $

  4. $200 \mathrm{kPa} $

Show answer
Correct Option: B
Explanation:

$\begin{array}{l} Given\, \, { P _{ 1 } }=200\, \, k\, pa \ { T _{ 1 } }=22^{ \circ  }C=273+22-295K \ { T _{ 2 } }=42^{ \circ  }C=273+42=315K \ PV=nRT \ \left( { \dfrac { { PV } }{ T }  } \right) ={ { constant } }\left[ \begin{array}{l} { { Since } }\, \, number\, \, of\, \, moles \ and\, \, R\, \, are\, \, { { constant } } \end{array} \right]  \ \dfrac { { { P _{ 1 } }{ V _{ 1 } } } }{ { { T _{ 1 } } } } =\dfrac { { { P _{ 2 } }{ V _{ 2 } } } }{ { { T _{ 2 } } } }  \ \dfrac { { 200\times 1 } }{ { 295 } } =\dfrac { { { P _{ 2 } }\left( { 1.02 } \right)  } }{ { 315 } }  \ { P _{ 2 } }=\dfrac { { 200\times 315 } }{ { 295\times 1.02 } } \, \, kPa \ = 209\, \, kPa \end{array}$

Option B.

A person blows into open-end of a long pipe. As a result, a high pressure pulse of air travels down the pipe. When this pulse reaches the other end of the pipe,

physics pressure in liquids and gases pressure dependence on force and area concept of pressure pressure on surface

  1. a high pressure pulse starts traveling up the pipe, it the other end of the pipe is open.

  2. a low pressure pulse starts traveling up the pipe, if the other end of the pipe is open.

  3. a low pressure pulse starts traveling up the pipe, if the other end ot the pipe is closed.

  4. a high pressure pulse starts traveling up the pipe, if the other end of the pipe is closed.

Show answer
Correct Option: D
Explanation:

A pressure wave undergoes a phase change of $ \pi$ radians on 

reflection from open end of no phase change occurs on reflection from 
closed end.