Which manometer reading shows more pressure within a liquid: a difference of 4 cm or 6 cm in the height of the liquid in two limbs of U tube?

The manometer is a device which is used to measure pressure exerted by the liquids. The difference in height of the liquid column in U-tubes gives the liquid pressure. We know that more the difference of densities of liquids, more will be the difference of height of the liquid column. Hence, 6 cm has a higher pressure difference when compared to 4 cm .

Torr is the unit of pressure, which is defined as the magnitude of force acting perpendicular to the surface of an object per unit surface area of the object. One torr is the pressure exerted by 1 mm of mercury column. 1 Torr = 133 . 3 Pa

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What is mercury barometer and its uses?

Important Questions on Mechanical Properties of Fluids

HARD

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

Consider a vessel filled with a liquid upto height

H .

The bottom of the vessel lies in the

X - Y

plane passing through the origin. The density of the liquid varies with

Z

-axis as

ρ (z) = ρ_{0} [2 - {(\frac{z}{H})}^{2}]

. If

P_{1}

and

P_{2}

are the pressures at the bottom surface and top surface of the liquid, the magnitude of

(P_{1} - P_{2})

is :

HARD

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

An open-ended U-tube of uniform cross-sectional area contains water (density $10^{3} kg m^{- 3}$ ). Initially the water level stands at $0.29 m$ from the bottom in each arm. Kerosene oil (a water-immiscible liquid) of density $800 kg m^{- 3}$ is added to the left arm until its length is $0.1 m$ , as shown in the schematic figure below. The ratio $(\frac{h_{1}}{h_{2}})$ of the heights of the liquid in the two arms is

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MEDIUM

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

U

tube with both ends open to the atmosphere is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of

10 mm

above the water level on the other side. Meanwhile, the water rises by

65 mm

from its original level (see diagram). The density of the oil is ____

(ρ_{w} = 1000 kg m^{- 3})

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

If pressure at half the depth of a lake is equal to

\frac{2}{3}

times the pressure at the bottom of the lake, then what is the depth of the lake?

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

What does a barometer measure?

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

At what speed will the velocity of a stream of water be equal to

20 c m

of mercury column? (Taking,

g = 10 m s^{- 2}

)

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

Torricelli's barometer used mercury. Pascal duplicated it using French wine of density $984 kg m^{- 3}$ . The height of the wine column for normal atmospheric pressure is

EASY

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

The pressure at depth

h

below the surface of a liquid of density

ρ

open to the atmosphere is

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

By sucking through a straw, a student can reduce the pressure in his lungs to

750 mm of Hg

(density

= 13.6 g {c m}^{- 3})

. Using the straw, he can drink water from a glass upto a maximum depth of

MEDIUM

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

_____ is a device used to measure the pressure exerted by liquids.

MEDIUM

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

Which manometer reading shows more pressure within a liquid: a difference of

4 cm

6 cm

in the height of the liquid in two limbs of U tube?

MEDIUM

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

Would you be able to suck juice with a drinking straw on the moon? Give a reason for your answer.

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

Find density of ethyl alcohol

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

What is torr?

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Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

A cubical sealed vessel with edge

L

is placed on a cart, which is moving horizontally with an acceleration

‘ a ’

as shown in figure. The cube is filled with an ideal fluid having density

d

. The gauge pressure at the centre of the cubical vessel is -

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MEDIUM

Physics>Mechanical Properties of Matter>Mechanical Properties of Fluids>Atmospheric Pressure and Gauge Pressure

During blood transfusion the needle is inserted in a vein where the gauge pressure is $2000 Pa$ . At what height (answer to two decimal places) must the blood container be placed so that blood may just enter the vein?

(Answer approximately to two decimal places)

(Use the density of whole blood from table).

Densities of some common fluids at STP

Fluid	$ρ (kg m^{- 3})$
Water Sea water Mercury Ethyl alcohol Whole blood Air Oxygen Hydrogen Intersteller space	$1.00 \times 10^{3}$ $1.03 \times 10^{3}$ $1.36 \times 10^{3}$ $0.806 \times 10^{3}$ $1.06 \times 10^{3}$ $1.29$ $1.43$ $9.0 \times 10^{- 2}$ $\approx 10^{- 22}$