Atmospheric Pressure

Q. A manometric liquid should ideally have

1. Low density and low vapour pressure
2. Low density and high vapour pressure
3. High density and low vapour pressure
4. High density and high vapour pressure

Q. Calculate the approximate height (h) of Earth's atmosphere extending above the surface of the Earth, assuming the density of air to be uniform [$1.3kg{m}^{-3}$] and pressure at the surface of Earth to be ${10}^{5}Pa$. (Assume the Earth to be perfectly spherical and no variation in 'g' due to height).

1. $6km<h<7km$

2. $5km<h<6km$

3. $7km<h<8km$

4. $8km<h<9km$

Q. Consider the barometer shown in figure. Density of mercury is $\rho$. A small hole is made at point $S$ as shown. The mercury comes out from this hole with speed $v$ equal to:

1. $\sqrt{2gh}$
2. $\sqrt{2gH}$
3. $\sqrt{2g(H-h)}$
4. None of the above

Q. The pans of a physical balance are in equilibrium. If air is blown under a pan, that pan will move down.

1. False
2. True

Q.

How is the barometric height of a simple barometer affected if

1. its tube is pushed down into the trough of mercury?
2. its tube is slightly tilted from vertical?
3. a drop of liquid is inserted inside the tube?

Q. Which of the following enables us to drink a liquid through a straw?

1. Humidity
2. Temperature
3. Atmospheric pressure
4. Composition of air

Q.

True atmospheric pressure is 74 cm of mercury at a given place. When a simple barometer is set up at that place, it records 76 cm. It is because:

1. Tube may be tilting

2. Area of the cross-section of the tube is too small

3. Mercury contains some dissolved metals

4. None of the above

Q. A barometer tube reads $76\text{cm}$ of $\text{Hg}$. If the tube is gradually inclined at an angle of ${30}^{\circ }$ with horizontal, then find the length of the mercury column in the barometer tube.

1. $142\text{cm}$
2. $152\text{cm}$
3. $132\text{cm}$
4. $122\text{cm}$

Q. Which of the following statements is/are correct?
(i) A simple U-tube manometer can measure negative gauge pressures.
(ii) Both ends of a U-tube manometer are exposed to the atmosphere. There exists a possibility that the height difference in the manometer is non-zero.

1. Only (i) is correct
2. Only (ii) is correct
3. Both (i) and (ii) are correct
4. None of these are correct

Q. Torricelli's barometer uses mercury of density $13.6\times {10}^3{\text{kg/m}}^3$. If mercury is replaced by wine of density $984{\text{kg/m}}^3$, then determine the height of the wine column for normal atmospheric pressure.

1. $760\text{m}$
2. $76\text{m}$
3. $10.5\text{m}$
4. $105\text{m}$

Q. Consider the barometer shown in figure. Density of mercury is $\rho$. A small hole is made at point $S$ as shown. The mercury comes out from this hole with speed $v$ equal to:

1. $\sqrt{2gh}$
2. $\sqrt{2gH}$
3. $\sqrt{2g(H-h)}$
4. None of the above

Q. A manometric liquid should ideally have

1. Low density and low vapour pressure
2. Low density and high vapour pressure
3. High density and low vapour pressure
4. High density and high vapour pressure

Q. Height of mercury in a barometer is $760\text{mm}$ at any location. If mercury is replaced by water then height of water will be :

1. $6.883\text{m}$
2. $10.336\text{m}$
3. $5.251\text{m}$
4. $8.521\text{m}$

Q. Consider the barometer shown in figure. If a small hole is made at point $A$ in the barometer tube, then

1. Mercury will come out from this hole after $10\text{sec}$
2. Mercury will not come out from this hole
3. First, mercury will come out and then stop after $10\text{sec}$
4. Mercury will come out from this hole after $15\text{sec}$

Q. Consider the barometer shown in figure. Density of mercury is $\rho$. A small hole is made at point $S$ as shown. The mercury comes out from this hole with speed $v$ equal to:

1. $\sqrt{2gh}$
2. $\sqrt{2gH}$
3. $\sqrt{2g(H-h)}$
4. None of the above

Q. A barometer tube reads $75\text{cm}$ of $Hg$. If the tube is gradually inclined at an angle of ${30}^{\circ }$ with the horizontal, keeping the open end in the mercury container, find the length of the mercury column in the barometer tube.

1. $86.7\text{cm}$
2. $150\text{cm}$
3. $75\text{cm}$
4. $92.5\text{cm}$

Q. A student wants to find the absolute pressure of water at a point below the surface of water. He has a barometer and a manometer pressure gauge. The barometer reads $1.3152\text{bar}$ whereas the manometer pressure gauge reads $0.3152\text{bar}$. What is the absolute pressure? (Assume that pressure at one end of the manometer is atmospheric.)

1. $1.6304\text{bar}$
2. $0.3152\text{bar}$
3. $1.3152\text{bar}$
4. $1\text{bar}$

Q. A barometer kept in an elevator at rest reads $76\text{cm}$ of $Hg$. If the elevator starts accelerating downwards, then the atmospheric pressure measured by the barometer (w.r.t column of mercury) in the elevator is:

1. $76\text{cm}$
2. $<76\text{cm}$
3. $>76\text{cm}$
4. zero