Tag: important points about atmospheric pressure

Questions Related to important points about atmospheric pressure

Why does water boil below $100^o$C at higher altitudes?

physics pressure in fluids and atmospheric pressure common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

  1. Pollution-free air at higher altitudes increases the calorific value of fuel used

  2. Water available at higher altitudes is purer than that in the plains

  3. There is lesser dissipation of heat at higher altitudes

  4. The atmospheric pressure at higher altitudes is low as compared to that at sea level

Show answer
Correct Option: D
Explanation:

As the atmospheric pressure is low at higher altitudes is compared to that sea level which causes decrease in boiling point as pressure is inversely proportional  the temperature. So, water does boil below $100^{\circ }C$ at higher altitude

 If the the height $(h)$ at which the atmospheric pressure is reduced to half. Find the value $\displaystyle h$.

physics pressure in fluids and atmospheric pressure common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

  1. $\displaystyle h=\dfrac{0.693RT}{Mg}$.

  2. $\displaystyle h=\dfrac{6.93RT}{Mg}$.

  3. $\displaystyle h=\dfrac{693RT}{Mg}$.

  4. None of these

Show answer
Correct Option: A
Explanation:

$\displaystyle P=P _{0}e^{-Mgh/RT} $
But $\displaystyle P=0.5P _{0}$
Hence, $\displaystyle 0.5P _{0}=P _{0}e^{-Mgh/RT} $
$\displaystyle 0.5=e^{-Mgh/RT} $


Take natural logarithm on both sides.
$\displaystyle \ln0.5=e^{-Mgh/RT} $
$\displaystyle -0.693 =  {-Mgh/RT}$
Hence, $\displaystyle \displaystyle h=\dfrac{0.693RT}{Mg} $

A fully loaded Boeing aircraft has a mass of $33\times 10^{5}$ kg. Its total wing area is $500 m^2$. It is in level flight with a speed of $960 km/h$. (a) Estimate the pressure difference between the lower and upper surfaces of the wings. (b) Estimate the fractional increase in the speed of the air on the upper surface of the wing relative to the lower surface. The density of air is $\rho = 1.2 kg m^{-3}$ and $g = 9.81 m^{-2}$.

physics pressure in fluids and atmospheric pressure common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

  1. $0.067$

  2. $0.075$

  3. $0.98$

  4. $0.88$

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Correct Option: B

Average density of air is:

physics pressure common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

  1. $\displaystyle 13600{ kg }/{ { m }^{ 3 } }$

  2. $\displaystyle 1.29{ kg }/{ { m }^{ 3 } }$

  3. Both

  4. All

Show answer
Correct Option: B
Explanation:

Average density of air is $\displaystyle 1.29{ kg }/{ { m }^{ 3 } }$ and the density of mercury as $\displaystyle 13600{ kg }/{ { m }^{ 3 } }$.

If the air pressure is below 76cm,we can say that air pressure has:

physics pressure common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

  1. Fallen

  2. Increased

  3. Both

  4. All

Show answer
Correct Option: A
Explanation:

If the barometric height is less than 76 cm,we can say that the air pressure has fallen,and if more than 76 cm ,we can say that air pressure has increased.

Which of the following causes change in air pressure?

physics pressure common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

  1. Height

  2. Season

  3. Temperature

  4. All

Show answer
Correct Option: D
Explanation:

it is found that with the change in height, season, temperature etc the barometric height changes, This indicates change in air pressure.