Tag: common consequences of the atmospheric pressure

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Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

Water barometer is possible provided barometer tube is _____$m$ long.

  1. $1$

  2. $3$

  3. $5$

  4. $11$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

If water would be used in barometer, barometer tube should have the huge height of $10.3m$ Mercury is $13.6$ times more dense than water and a column weight of only $760 mm$ of Hg equals the forces generated by atmospheric pressure, so the tube can be much shorter.

Mercury is more dense. Its relative density is $13.534$ times that of water. So, to measure the atmospheric pressure, which is $760 mm$ of mercury you need a barometer ,with mercury, of length slightly more than $0.76 m$, say one meter to cover the special cases of some higher pressure. If you use water, you have to have the length of barometer of length (or height)  $13.534$ times the length of mercury barometer, which may be more than $11 m$ in length. Further mercury, being a metal has the shining quality which highlight its reading clear. Also mercury, having comparatively lower specific heat and good conductor of heat, could come to the same temperature of the atmosphere more quickly.

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

Water is not used as a barometric liquid because 

  1. it is difficult to have a barometer tube 11 m long.

  2. water vaporises under vacuum conditions.

  3. water sticks to the side of glass tube.

  4. all the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mercury is more dense. Its relative density is $13.534$ times that of water. So, to measure the atmospheric pressure, which is $760 mm$ of mercury you need a barometer ,with mercury, of length slightly more than $0.76 m$, say one meter to cover the special cases of some higher  pressure. If you use water, you have to have the length of barometer of  length (or height)  $13.534$ times the length of mercury barometer, which  may be more than $11 m$ in length. 


Further mercury, being a metal has the shining quality which highlight its reading clear. Also mercury, having comparatively lower specific heat and good conductor of heat, could come to the same temperature of the atmosphere more quickly.

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

The weight of the column of the mercury in the tube above the surface of the mercury in the cup is balanced by

  1. The weight of air column

  2. Friction Force

  3. Viscous Force

  4. Buoyant force
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A

The weight of mercury column is balanced by air weight and the weight of mercury column is used to calculate the pressure. 

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

Which of the following scientists invented the mercury barometer?

  1. Blaise Pascal

  2. Evangelist Torricelli

  3. James Joule

  4. Robert Brown
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mercury barometer was invented by scientist Evangelist Torricelli

It is known fact
Therefore option $B$ is correct 

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

A barometer kept in a stationary elevator reads $76$ cm. If the elevator starts accelerating up the reading will be:

  1. Zero

  2. Equal to $76$cm

  3. More than $76$cm

  4. Less than $76$cm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The movement of elevator up will increase value of g which will result in increase in pressure leading to increase in reading of barometer.

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

A nurse measures the blood pressure of a seated patient to be $190$ mm of Hg.

  1. the blood pressure at the patient's feet is less than $190$ mm of Hg.

  2. the actual pressure is about $0.25$ times the atmospheric pressure.

  3. the blood pressure at the patient's neck is more than $190$ mm of Hg.

  4. the actual pressure is about $1.25$ times the atmospheric pressure.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

${ P } _{ exp }=P _{ 0 }+{ P } _{ Actual }\ 190=76+{ P } _{ Actual }\ { P } _{ Actual }=114mm\quad of\quad Hg\ Factor=\cfrac { { P } _{ Actual } }{ { P } _{ atm } } =\cfrac { 114 }{ 76 } \approx 1.25$

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

Match the following.

List-I(Measuring Instruments) List-II(Which measure)
A. Anemometer $1$. Motor Power
B. Tachometer $2$. Wind speed
C. Dynamometer $3$. Revolutions per minute
D. Barometer $4$. Atmospheric pressure
$5$. Current from a dynamo

  1. A-$2$, B-$3$, C-$1$, D-$4$

  2. A-$2$, B-$1$, C-$3$, D-$4$

  3. A-$1$, B-$3$, C-$5$, D-$4$

  4. A-$1$, B-$3$, C-$5$, D-$2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Anemometers measure wind speed (A-2), tachometers measure RPM (B-3), dynamometers measure power/force (C-1), and barometers measure atmospheric pressure (D-4). This matches option A.

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

A barometer kept in a stationary elevator reads 76 cm. If the elevator starts accelerating up, the reading in barometer will be:

  1. Zero

  2. Equal to 76 cm

  3. More than 76 cm

  4. Less than 76 cm
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Since the elevator is accelerating up, so, the force will act in the downward direction.

Therefore, the reading in the barometer will be less than 76 cm

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

The atmospheric pressure and height of barometer column is $10^5 P _a$ and 760mm respectively on the earth surface. If the barometer is taken to moon then column height will be

  1. zero

  2. 76 mm

  3. 126.6 mm

  4. 760 mm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since there is no atmosphere on moon, no atmospheric pressure will be there and hence corresponding to 0 pressure, height of mercury column will be 0.


Answer is option A.

Multiple choice physics pressure in liquids and gases common consequences of the atmospheric pressure atmospheric pressure and its consequences important points about atmospheric pressure

Fill in blanks. 
Atmosphere pressure _________ with increase in altitude 

  1. increases

  2. decreases

  3. remains same

  4. cannot be determined
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Pressure with Height: pressure decreases with increasing altitude. The pressure at any level in the atmosphere may be interpreted as the total weight of the air above a unit area at any elevation. At higher elevations, there are fewer air molecules above a given surface than a similar surface at lower levels. For example, there are fewer molecules above the 50 km surface that are found above the 12 km surface, which is why the pressure is less at 50 km.

Hence, Atmosphere pressure decrease with an increase in altitude