A barometer kept in an elevator reads 76cm when it is at rest. If the elevator goes up with increasing speed, the reading will be:
- Azero.
- B76cm.
- ✓< 76cm.
- D> 76cm.
Answer: C.
View full solution →Question types
Fluid Mechanics question types
75 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
75
Questions
6
Question groups
5
Question types
01
M.C.Q (1 Marks)
24 Q→021 Marks Question
23 Q→032 Marks Questions
16 Q→043 Marks Question
5 Q→055 Marks Questions
3 Q→06Case study (4 Marks)
4 Q→Sample Questions
Fluid Mechanics questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
Suppose the pressure at the surface of mercury in a barometer tube is $P_1$ and the pressure at the surface of mercury in the cup is $P_2,$
- ✓$P_1=0, P_2=$ atmospheric pressure.
- B$\mathrm{P}_1=$ atmospheric pressure $\mathrm{P}_2=0$
- C$P_1=P_2=$ atmospheric pressure.
- D$P_1=P_2=0$
Answer: A.
View full solution →Consider the equations$\text{P}=\lim_\limits{\triangle\text{s}\rightarrow0}\frac{\text{F}}{\triangle\text{s}}$ and $\text{P}_1-\text{P}_2-\text{pgz}$
In an elevator accelerating upward.
In an elevator accelerating upward.
- ABoth the equations are valid.
- ✓The first is valid but not the second.
- CThe second is valid but not the first.
- DBoth are invalid.
Answer: B.
View full solution →Water enters through end $A$ with a speed $v_1$ and leaves through end $B$ with a speed $v_2$ of a cylindrical tube $AB$. The tube is always completely filled with water. In case $I$ the tube is horizontal, in case $II$ it is vertical with the end $A$ upward and in case $III$ it is vertical with the end $B$ upward. We have $v_1= v_2$ for
- ACase $I$.
- BCase $II.$
- CCase $III.$
- ✓Each case.
Answer: D.
View full solution →Bernoulli's theorem is based on conservation of:
- AMomentum.
- BMass.
- ✓Energy.
- DAngular momentum.
Answer: C.
View full solution →Suppose the tube in the previous problem is kept vertical with B upward. Water enters through B at the rate of $1cm^3/s$ . Repeat parts (a), (b) and (c). Note that the speed decreases as the water falls down.
View full solution →A ferry boat loaded with rocks has to pass under a bridge. The maximum height of the rocks is slightly more than the height of the bridge so that the boat just fails to pass under the bridge. Should some of the rocks be removed or some more rocks be added?
Solve the previous problem if the lead piece is fastened on the top surface of the block and the block is to float with its upper surface just dipping into water.
Water is slowly coming out from a vertical pipe. As the water descends after coming out, its area of cross-section reduces. Explain this on the basis of the equation of continuity.
A barometer tube reads 76cm of mercury. If the tube is gradually inclined keeping the open end immersed in the mercury reservoir, will the length of mercury column be 76cm, more than 76cm or less than 76cm?
If water be used to construct a barometer, what would be the height of water column at standard atmospheric pressure (76cm of mercury)?
A U- tube containing a liquid is accelerated horizontally with a constant acceleration $a_0$. If the separation between the vertical limbs is 1, find the difference in the heights of the liquid in the two arms.
View full solution →A solid sphere of radius 5cm floats in water. If a maximum load of 0.1kg can be put on it without wetting the load, find the specific gravity of the material of the sphere.
A metal piece of mass 160g lies in equilibrium inside a glass of water The piece touches the bottom of the glass at a small number of points. If the density of the metal is $8000kg/m^3$, find the normal force exerted by the bottom of the glass on the metal piece.
View full solution →Water flows through a horizontal tube of variable cross-section. The area of cross-section at A and B are $4mm^2$ and $2mm^2$ respectively. If 1cc of water enters per second through A, find,
View full solution →- The speed ofwater at A.
- The speed of water at B.
- Thepressure difference $P_A - P_B$.
A cube of ice of edge 4cm is placed in an empty cylindrical glass of inner diameter 6cm. Assume that the ice melts uniformly from each side so that it always retains its cubical shape. Remembering that ice is lighter than water, find the length of the edge of the ice cube at the instant it just leaves contact with the bottom of the glass.
A cylindrical object of outer diameter 10cm, height 20cm and density $8000kg/m^3$ is supported by a vertical spring and is half dipped in water as shown in.
View full solution →- Find the elongation of the spring in equilibrium condition.
- If the object is slightly depressed and released, find the time period of resulting oscillations of the object. The spring constant = 500N/m.
A glass full of water has a bottom of area $ 20cm^2,$ top of area $20cm^2$, height 20cm and volume half a litre.
View full solution →-
Find the force exerted by the water on the bottom.
-
Considering the equilibrium of the water, find the.
Suppose the glass of the previous problem is covered by a jar and the air inside the jar is completely pumped out.
-
What will be the answers to the problem?
-
Show that the answers do not change if a glass of different shape is used provided the height, the bottom area and the volume are unchanged.
Water is filled in a rectangular tank of size 3m × 2m × 1m.
View full solution →-
Find the total force exerted by the water on the bottom surface of the tank.
-
Consider a vertical side of area 2m × 1m. Take a horizontal strip of width ox metre in this side, situated at a depth of x metre from the surface of water. Find the force by the water on this strip.
-
Find the torque of the force calculated in part.(b) about the bottom edge of this side.
-
Find the total force by the water on this side.
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Find the total torque by the water on the side about.
A cubical metal block of edge 12cm floats in mercury with one fifth of the height inside the mercury. Water is poured till the surface of the block is just immersed in it. Find the height of the water column to be poured. Specific gravity of mercury = 13.6.
Water leaks out from an open tank through a hole of area $2mm^2$ in the bottom. Suppose water is filled up to a height of 80cm and the area of cross-section of the tank is $0.4m^2$. The pressure at the open surface and at the hole are equal to the atmospheric pressure. Neglect the small velocity of the water near the open surface in the tank.
View full solution →- Find the initial speed of water coming out of the hole.
- Find the speed of water coming out when half of water has leaked out.
- Find the volume of water leaked out during a time interval dt after the height remained is h. Thus find the decrease in height dh in terms of h and dt.
- From the result of part c find the time required for half of the water to leak out.
An ornament weighing 36g in air, weighs only 34g in water. Assuming that some copper is mixed with gold to prepare the ornament, find the amount of copper in it. Specific gravity of gold is 19.3 and that of copper is 8.9.
In the derivation of $P_1 - P_2 = Pgz,$ it was assumed that the liquid is incompressible. Why will this equation not be strictly valid for a compressible liquid?
View full solution →Suppose the density of air at Madras is $P_0$ and atomospheric pressure is $P_0$. If we go up, the density and the pressure both decrease. Suppose we wish to calculate the pressure at a height 10km above Madras. If we use the equation $P_0- P =$ pogz, will we get a pressure more than the actual or less than the actual? Neglect the variation in g. Does your answer change if you also consider the variation in g?
View full solution →While watering a distant plant, a gardener partially water than in fresh closes the exit hole of the pipe by putting his finger on it. Explain why this results in the water stream goirig to a larger distance.
Refer to the previous problem. Suppose, the goldsmith argues that he has not mixed copper or any other material with gold, rather some cavities might have been left inside the ornament. Calculate the volume of the cavities left that will allow the weights given in that problem.
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