Tag: introduction to atmospheric pressure

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Questions Related to introduction to atmospheric pressure

Multiple choice physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

By sucking through a straw, a student can reduce the pressure in his lungs to $750 mm$ of Hg (density = $\displaystyle 13.6{ gm }/{ { cm }^{ 3 } }$). Using the straw, he can drink water from a glass upto a maximum depth of: 

  1. $10 cm$
  2. $75 cm$
  3. $13.6 cm$
  4. $1.36 cm$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pressure difference created $= 10 mm$ of Hg 
This must be equal to the pressure of water column being created in the straw. If height of water column be $h$

$h \rho g = \dfrac{10}{10} \times 13.6 g$
$hg \times 1 = 13.6 g$
$h = 13.6 cm$

Multiple choice physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

One gram mole of oxygen is enclosed in a vessel at a temperature of $27$ and at one atmospheric pressure. The vessel is thermally insulated and is moved with a constant speed $u _0$. Calculate $u _0$ if the rise in temperature is $1K$ when the vessel is suddenly stopped?

  1. $35.6 m/s$
  2. $45 m/s$
  3. $90 m/s$
  4. $60 m/s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

since internal energy depends only on the temperature ,

as the temperature changes,
the change in internal energy is
$\Delta U= \dfrac{nfR \Delta T}{2}$

vessel contains a gas of mass M,
change in kinetic energy $= \dfrac{nMv^2}{2}$

$\dfrac{nfR \Delta T}{2}$= $\dfrac{nMv^2}{2}$

$\dfrac{2}{\dfrac{c _p}{c _v} - 1}$

$f = \dfrac{2}{\dfrac{2}{5}}$ = 5

putting value

$v = 45 m/s$

Multiple choice physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

What will be the pressure in pascal due to a mercury column of $76$cm. Density of mercury is $13.6$ g$cm^2$, $g=980$ cm$s^2$?

  1. $1.0129\times 10^5$Pa
  2. $1.0129\times 10^4$Pa
  3. $1.0129\times 10^3$Pa
  4. $1.0129\times 10^2$Pa
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 h$=76cm$

Pressure=?

Formula to be used : $P=hgd$

Where h = height of mercury column and

 d= density of mercury$=13.6 gm/cc$

acceleration due to gravity$=980 cm/s²$

$P=hgd=13.6\times 980\times 76=1012928dyne.cm²$

Multiple choice physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

The height of the mercury column in a simple barometer is $h$. As the tube is inclined with the vertical at an angle $\alpha$, the length of the mercury column along the length of the tube will become:

  1. $h\cos{\alpha}$
  2. $\dfrac{h}{\cos{\alpha}}$
  3. $h\sin{\alpha}$
  4. $\dfrac{h}{\sin{\alpha}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Similar to question 480419, the vertical height h is the projection of the length l along the tube, so h = l * cos(alpha), which means l = h / cos(alpha).

Multiple choice physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure devices to measure pressure
At sea level, the vertical height of mercury supported in the tube of simple barometer is ______ $cm$ above the mercury level in the bowl.
  1. $36$
  2. $76$
  3. $100$
  4. $7$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The height to which mercury rises in simple barometer is $76cm$.

This is the reason that  atmospheric pressure is often expressed as $76cm$ of Hg at sea level.

Multiple choice physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure devices to measure pressure
The vacuum created in simple barometer is known as __________ vacuum

  1. Newton's

  2. Barometric

  3. Torricellian

  4. Archimedes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A simple barometer or a mercury barometer has a glass tube closed at one end with an open mercury-filled reservoir at the base. The weight of the mercury creates a vacuum in the top of the tube known as Torricellian vacuum.