Tag: fluids

Questions Related to fluids

In a certain region of space, there are n molecules per unit volume. The temperature of the gas T. The pressure of the gas will be: 

various types of barometer fluids physics

  1. $nRT$

  2. $nkT$

  3. $\dfrac{{nT}}{k}$

  4. $\dfrac{{nT}}{R}$

Show answer
Correct Option: B

How is the barometric height of a simple barometer affected if
(a) its tube is pushed down into the trough of mercury?
(b) its tube is slightly tilted form vertical?
(c) a drop of liquid is inserted inside the tube?

various types of barometer fluids physics

  1. (a) remains unaffected (b) increases (c) decreases

  2. (a) decreases (b) increases (c) decreases

  3. (a) increases (b) remains unaffected (c) increases

  4. (a) remains unaffected (b) remains unaffected (c) decreases

Show answer
Correct Option: D
Explanation:

Below are the answers:
(a) Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column. Low pressure allows the mercury to drop to a lower level in the column by lowering the force placed on the reservoir.
When the tube is pushed down into the trough of mercury the height of mercury column above the surface of the bottom surface remains the same. 


(b) When the tube is slightly tilted form vertical, there is no change in the height of the mercury in the tube.

(c) If the vacuum is replaced with a drop, then the drop will exert some pressure on the mercury and there will be inaccurate readings on the barometer. The barometric height is decreased in this case. So, vacuum is present on top of the mercury inside the tube.

Which of the following is not a reason why mercury is preferred as a barometric liquid?

various types of barometer fluids physics

  1. Mercury has high density

  2. Mercury does not wet the glass

  3. Mercury is opaque and shiny

  4. Mercury is poisonous

Show answer
Correct Option: D
Explanation:

1) It has $13.5$ times higher density than water
2) It doesn't stick to the glass walls of tube like water does.

3) It is opaque and shiny

Atmospheric pressure at a place is $66cm$ of mercury. This place is

various types of barometer fluids physics

  1. $1250m$ above sea level

  2. $1250m$ below sea level

  3. $125m$ above sea level

  4. at the sea level

Show answer
Correct Option: A
Explanation:

Atmospheric pressure at the place is equivalent to that of $66cm$ of mercury.
We know that atmospheric pressure at the sea level is equivalent to that of $76cm$ of mercury.
So, pressure at that place is less by $(76-66)=10cm$ of mercury.
We know that atmospheric pressure decreases by $1cm$ for every $125m$ increase in altitude.
So, the concerned place is $(125 \times 10)m=1250m$ above the sea level.

If the mass of the sheet at the top of the aneroid barometer used as an altimeter is increased, what will be the effect on the reading?

various types of barometer fluids physics

  1. It will reduce.

  2. It will increase.

  3. No effect.

  4. Can't be determined

Show answer
Correct Option: B
Explanation:

If the top sheet in an aneroid barometer is heavier, it will displace lesser. So, it gives reading corresponding to a lower pressure with a lighter thin sheet. Lower pressure is observed at more heights and hence, the reading of the altimeter will increase.

Water vaporizes under vacuum conditions. Mark the statement which is correct with respect to using water as a barometric fluid.

various types of barometer fluids physics
  1. It will show the true atmospheric pressure.
  2. It will be clearly seen in the glass tube.
  3. It will not show true atmospheric pressure.

  4. None

Show answer
Correct Option: C
Explanation:

WATER VAPORISES UNDER VACUUM CONDITIONS.THUS WATER BAROMETER WILL NOT SHOW TRUE ATMOSPHERIC PRESSURE.

Atmospheric pressure at a certain place is equivalent to $78cm$ of mercury. That place is

various types of barometer fluids physics

  1. $250m$ above sea level

  2. $250m$ below sea level

  3. $125m$ above sea level

  4. at the sea level

Show answer
Correct Option: B
Explanation:

Atmospheric pressure at that place is $78cm$ of mercury.
We know that the atmospheric pressure at the sea level is $76cm$ of mercury.
This means, this place has an atmospheric pressure $(78-76)cm=2cm$ more than the atmospheric pressure at the sea level.
We know that the atmospheric pressure increases by $1cm$ for every $125m$ decrease in height.
So, this place is $(125 \times 2)m=250m$ below sea level.

Gradual fall in the mercury level in a barometer indicates
various types of barometer fluids physics

  1. possibility of rain

  2. possibility of thunderstorm

  3. fair weather

  4. dry and sunny weather

Show answer
Correct Option: A
Explanation:

Gradual fall in the mercury level occurs at low pressure- If there is too much moisture in the air, indicates the possibility of rain

Which is the most accurate instrument to measure pressure and is used as a standard?

various types of barometer fluids physics

  1. Aneroid Barometer

  2. Mercury Barometer

  3. Barograph

  4. Manometer

Show answer
Correct Option: B
Explanation:

Answer is B

In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured. To increase their accuracy, mercury barometers are often corrected for ambient temperature and the local value of gravity.

A barometer which measures atmospheric pressure more accurately is ..........

physics fluids pressure in fluids pressure in liquids introduction to pressure

  1. Fortin's barometer

  2. mercury barometer

  3. anaeroid barometer

  4. Torricelli barometer

Show answer
Correct Option: B
Explanation:

A barometer which measures atmospheric pressure most accurately is mercury barometer.

Hence, option B is correct.