Advertisements
Advertisements
Question
Does it matter if one uses gauge instead of absolute pressures in applying Bernoulli’s equation? Explain.
Advertisements
Solution
No
It does not matter if one uses gauge pressure instead of absolute pressure while applying Bernoulli’s equation. The two points where Bernoulli’s equation is applied should have significantly different atmospheric pressures.
APPEARS IN
RELATED QUESTIONS
During blood transfusion the needle is inserted in a vein where the gauge pressure is 2000 Pa. At what height must the blood container be placed so that blood may just enter the vein? [Use the density of whole blood from Table 10.1].
Consider the barometer shown in the following figure. If a small hole is made at a point P in the barometer tube, will the mercury come out from this hole?

The three vessels shown in the following figure have same base area. Equal volumes of a liquid are poured in the three vessels. The force on the base will be
Equal mass of three liquids are kept in three identical cylindrical vessels A, B and C. The densities are ρA, ρB, ρC with ρA < ρB < ρC. The force on the base will be
Shows in the following figure a siphon. The liquid shown is water. The pressure difference PB − PAbetween the points A and B is
Suppose the pressure at the surface of mercury in a barometer tube is P1 and the pressure at the surface of mercury in the cup is P2.
A barometer kept in an elevator reads 76 cm when it is at rest. If the elevator goes up with increasing speed, the reading will be ______.
Figure shows a capillary tube of radius r dipped into water. If the atmospheric pressure is P0, the pressure at point A is

The surface of water in a water tank on the top of a house is 4 m above the tap level. Find the pressure of water at the tap when the tap is closed. Is it necessary to specify that the tap is closed?
The weight of an empty balloon on a spring balance is W1. The weight becomes W2when the balloon is filled with air. Let the weight of the air itself be w. Neglect the thickness of the balloon when it is filled with air. Also neglect the difference in the densities of air inside and outside the balloon.
(a) W2 = W1
(b) W2 = W1 + w
(c) W2 < W1 + w
(d) W2 > W1
A closed vessel is half filled with water. There is a hole near the top of the vessel and air is pumped out from this hole.
(a) The water level will rise up in the vessel.
(b) The pressure at the surface of the water will decrease
(c) The force by the water on the bottom of the vessel will decrease
(d) The density of the liquid will decrease
A glass full of water has a bottom of area 20 cm2, top of area 20 cm2, height 20 cm and volume half a litre.
(a) Find the force exerted by the water on the bottom.
(b) Considering the equilibrium of the water, find the resultant force exerted by the sides of the glass on the water. Atmospheric pressure = 1.0 × 105 N/m2. Density of water 1000 kg/m3 and g = 10 m/s2. Take all numbers
to be exact.

If water be used to construct a barometer, what would be the height of water column at standard atmospheric pressure (76 cm of mercury) ?
A U-tube containing a liquid is accelerated horizontally with a constant acceleration a0. If the separation between the vertical limbs is l, find the difference in the heights of the liquid in the two arms.
Pressure decreases as one ascends the atmosphere. If the density of air is ρ, what is the change in pressure dp over a differential height dh?
Considering the pressure p to be proportional to the density, find the pressure p at a height h if the pressure on the surface of the earth is p0.
A glass capillary sealed at the upper end is of length 0.11 m and internal diameter 2 × 10-5 m. This tube is immersed vertically into a liquid of surface tension 5.06 × 10-2 N/m. When the length x × 10-2 m of the tube is immersed in liquid then the liquid level inside and outside the capillary tube becomes the same, then the value of x is ______ m. (Assume atmospheric pressure is 1.01 × 105 `"N"/"m"^2`)
