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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Statement 1 is false, statement 2 is true. Statement-1: The speed of liquid coming out of the orifice is independent of the nature and quality of liquid in the container.A. Statement-I is true, statement-2 true and statements-2 is a correct explanation for statements-5B. Statement 1 is true, statement 2 is true, statement-2 is not a correct explanation for statement 5C. Statement 1 is true, statement 2 is falseD. Statement 1 is false, statement 2 is true |
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Answer» Correct Answer - C Statement -2 is wrong |
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| 2. |
Statement-1 : When an orifice is made in the middle of the wall of a vessel, the range of the liquid coming out of the orifice is equal to the height of the liquid. Statement-2 : Liquid is flowing through two identical pipes A and B. Volume of liquid flowing per second through A and B are `v_(0) and 2v_(0)` respectively. Flow in A is turbulent and steady in B. Statement-3 : Rate of flow of a viscous liquid through a pipe is directly proportional to he fourth power of the radius of pipe.A. T T TB. T T FC. F F TD. F T T |
| Answer» Correct Answer - C | |
| 3. |
Statement-1 : Bernoullis equation is based on energy conservation. Statement-2 : Bernoullis equation can only be applied if the flow is streamlined. Statement-3 : Bernoullies equation can be applied evern if the flow is not streamlined as total energy is always conserved.A. T T TB. T F TC. T T FD. F F F |
| Answer» Correct Answer - C | |
| 4. |
An ideal fluid flows through a pipe of circular cross-section made of two sections with diameters `2.5 cm` and `3.75 cm`. The ratio of the velocities in the two pipes isA. `9:4`B. `3:2`C. `sqrt(3):sqrt(2)`D. `sqrt(2):sqrt(3)` |
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Answer» Correct Answer - A According to equation of continuity `a_(1)v_(1)=a_(2)v_(2)` or `(v_(1))/(v_(2))=(a_(2))/(a_(1))=(pid_(2)^(2)//4)/(pid_(1)^(2)//4)=((d_(2))/(d_(1)))^(2)=((3.75)/(2.50))^(2)=(9)/(4)` |
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| 5. |
The angle of contact between glass and water is `0^@` and surface tension is `70 dyn//cm`. Water rises in a glass capillary up to `6 cm`. Another liquid of surface tension `140 dyn//cm`, angle of contact `60^@` and relative density `2` will rise in the same capillary up toA. 12 cmB. 24 cmC. 3 cmD. 6 cm |
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Answer» Correct Answer - C `(h_(2))/(h_(1))=(sigma_(2)costheta_(2))/(rho_(2))xx(rho_(1))/(sigma_(1)costheta_(1))` Or `(h_(1))/(hl_(2))=(140xx(1)/(2))/(2)xx(1)/(70xx1)` or `h_(2)=(h_(1))/(2)=(6)/(2)cm=3cm` |
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| 6. |
The potential energy of the liquid of surface tension `T` and density `rho` that rises into the capillary tube isA. `pi^(2)T^(2)rho^(2)g`B. `4piT^(2)rho^(2)g`C. `(2piT^(2))/(rhog)`D. `(piT^(2))/(rhog)` |
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Answer» Correct Answer - C `P.E=mg(h//2)=pir^(2)hrhog h//2` |
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| 7. |
The radii of the two columne is U-tube are `r_(1)` and `r_(2)(gtr_(1))`. When a liquid of density `rho` (angle of contact is `0^@))` is filled in it, the level different of liquid in two arms is h. The surface tension of liquid is `(g=` acceleration due to gravity)A. `(rhoghr_(1)r_(2))/(2(r_(2)-r_(1))`B. `(rhogh(r_(2)-r_(1)))/(2r_(2)r_(1))`C. `(2(r_(1)-r_(2)))/(rhoghr_(2)r_(1))`D. `(2(r_(1)-r_(2)))/(rhogh)` |
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Answer» Correct Answer - A `h=(2T)/(dg)[(1)/(r_(1))-(1)/(r_(2))]` |
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| 8. |
The radii of the two columne is U-tube are `r_(1)` and `r_(2)(gtr_(1))`. When a liquid of density `rho` (angle of contact is `0^@))` is filled in it, the level different of liquid in two arms is h. The surface tension of liquid is `(g=` acceleration due to gravity)A. `(rhoghr_(1)r_(2))/(2(r_(2)-r_(1)))`B. `(rhogh(r_(1)-r_(2)))/(2r_(1)r_(2))`C. `(2(r_(2)-r_(1)))/(rhoghr_(1)r_(2))`D. `(rhogh)/(2(r_(2)-r_(1)))` |
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Answer» Correct Answer - A Let `h_(1), h_(2)` be the heights to which liquid rises in two columns of radii `r_(1)` and `r_(2)` respectively. Then `h_(1)=(2ScosO^(@))/(r_(1)rhog)=(2S)/(r_(1)rhog)` Where s is the surface tension of liquid. and `h_(2)=(2Scoso^(@))/(r_(2)rhog)=(2S)/(r_(2)rhog)` `therefore` Difference in levels of liquid in two arms of U tube is `h=h_(1)-h_(2)=(2S)/(rhog)[(1)/(r_(2))-(1)/(r_(2))]=2S((r_(2)-r_(1)))/(r_(1)r_(2)rhog)` `S=(r_(1)r_(2)rhogh)/(2(r_(2)-r_(1)))` |
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| 9. |
A spherical ball of radius `3.0xx10^(-4)` m and density `10^(4)(kg)/(m^(3))` falls freely under gravity through a distance `H=nxx500m` before entering a tank of water. If after enerting the water the velocity of the ball does not change, then find n. viscosity of water is `10xx10^(-6)(N-s)/(m^(2))`,`g=10(m)/(s)` |
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Answer» Correct Answer - 5 `V=2r^(2)(rhog)/(9eta)` and `V=sqrt(2gH)` |
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| 10. |
The two thigh bones (femur bones) each of cross-sectional area `10 cm^(2)` support the upper part of a human body of mass 40 kg . Estimate the average pressure sustained by the femurs. `g=10m//s^(2)` |
| Answer» `2 xx 10^(5) N m^(-2)` | |
| 11. |
Two soap bubbles of radii 2 cm and 3 cm are brought in contact. Find the radius of curvature (in cm) of the contact surface. |
| Answer» Correct Answer - 6 | |
| 12. |
If two soap bubbles of different radii are connected by a tubeA. air flows from the bigger bubbles to the smaller bubble till the sizes become equal.B. air flows from bigger bubble to the smaller bubble till the sizes are interchangedC. air flows from the smaller bubble to the bigger.D. there is no flow of air. |
| Answer» Correct Answer - C | |
| 13. |
Two soap bubbles `A` and `B` are kept in a closed chamber where the air is maintained at pressure `8 N//m^(2)`. The radii of bubbles `A` and `B` are `2 cm` and `4 cm`, respectively. Surface tension of the soap. Water used to make bubbles is `0.04 N//m`. Find the ratio `n_(B)//n_(A)`, where `n_(A)` and `n_(B)` are the number of moles of air in bubbles `A` and `B` respectively. [Neglect the effect of gravity.]A. 2B. 4C. 6D. 8 |
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Answer» Correct Answer - C The excess of pressure above atmospheric pressure, due to surface tension in a bubble`=(4T)/(r)` The surronding pressure `P_(0)=8 N/m^(2)` `therefore P_(A)` for `1^(st)` bubble `=P_(0)+(4T)/(r_(A))=8+(4xx0.04)/(0.02)` `P_(A)=16N//m^(2)` `P_(B)=P_(0)+(4T)/(r_(A))=12N//m^(2)` `PV=nRT` `(16)(4)/(3)pi(0.02)^(3)=n_(A)RT` `(12)((4)/(3)pi(0.04)^(3))=n_(B)RT` `(n_(B))/(n_(A))=6` |
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| 14. |
The radii of two air bubbles are in the ratio 4 : 5. Find the ratio of excess pressure inside them. Also compare the works done in blowing these bubbles. |
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Answer» Let the radii of two air bubbles be `r_(1) = 4 R` `r_(2) = 5 R` If the respective excess pressures are `Delta P_(1) and Delta P_(2)` Then `Delta P_(1) = (4S)/(r_(1))` `Delta P_(2) =(4S)/(r_(2))` `(Delta P_(1))/(Delta P_(2))=(r_(2))/(r_(1))=(5)/(4)` Work done in blowing the bubbles are `W_(1) = S xx 2 xx 4 pi r_(1)^(2)` `W_(2) = S xx 2 xx 4 pi r_(2)^(2)` Thus `(W_(1))/(W_(2))=((r_(1))/(r_(2)))^(2)=((4)/(5))^(2)` `=(16)/(25)` |
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| 15. |
A solid ball of mass 5 kg occupies a volume of 240 `cm^(3)`. How much will it weigh when immersed completely in a fluid of dnesity `2.7 xx 10^(3)` kg `m^(-3)`? Hint : Apparent weight = Actual weight - Buoyant force |
| Answer» Correct Answer - 42.65 N | |
| 16. |
If a block of iron (density `5 g cm^(-3))` is size 5 cm x 5 cm x 5 cm was weight while completely submerged in water, what would be the apparent weight ?A. `5xx5xx5xx5` gm wtB. `4xx4xx4xx4` gm wtC. `3xx5xx5xx5` gm wtD. `4xx5xx5xx5` gm wt |
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Answer» Correct Answer - 4 Apparent Weight `=mg[1-(d_(1))/(d_(b))]` |
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| 17. |
Statement-1 : Two bodies of different masses and shapes may experience same thrust in a given liquid. And Statement-2 : The buoyancy is independent of factors of the body such as its mass and shape.A. Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1B. Statement-1 is True, Statement-2 is True, Statement-2 is not a correct explanation for Statement-1C. Statement-1 is True, Statement-2 is FalseD. Statement-1 is False, Statement-2 is True |
| Answer» Correct Answer - A | |
| 18. |
Statement-1 : Pressure on a body is always compressive while stress can be compressive or tensile. And Statement-2 : Pressure is always normal to the area while stress can be either normal or tangential.A. Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1B. Statement-1 is True, Statement-2 is True, Statement-2 is not a correct explanation for Statement-1C. Statement-1 is True, Statement-2 is FalseD. Statement-1 is False, Statement-2 is True |
| Answer» Correct Answer - D | |
| 19. |
A wooden cylinder of diameter 4r height h and density `(rho)/(3)` is kept on a hole of diameter 2r of a tank, filled with water of density `rho` as shown in the figure. The height of the base of cylinder from the base of tank is H. What is the value of additional force required to hold the block in the given situation, if the water level just grazes the top surface of the blockA. `(5)/(4) mg`B. `(5)/(3) mg`C. `(4)/(3) mg`D. `(3)/(4) mg` |
| Answer» Correct Answer - A | |
| 20. |
A liquid is filled in a vessel and a hole is made at a depth h below the free surface of the liquid. Statement-1 : Greater is the distance of the hole form the free surface of liquid, greater will be the velocity of efflux. And Statement-2 The speed of the liquid coming out of the orifice depends on the quantity of liquid in the vessel.A. Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1B. Statement-1 is True, Statement-2 is True, Statement-2 is not a correct explanation for Statement-1C. Statement-1 is True, Statement-2 is FalseD. Statement-1 is False, Statement-2 is True |
| Answer» Correct Answer - C | |
| 21. |
A wooden cylinder of diameter 4 r, height H and density `rho//3` is kept on a hole of diameter 2 r of a tank, filled with water of density `rho` as shown in the The block in the above question is maintained by external means and the level of liquid is lowered. The height `h_(2)` when this external force reduces to zero is A. `(h)/(3)`B. `(4h)/(9)`C. `(2h)/(3)`D. h |
| Answer» Correct Answer - B | |
| 22. |
The pressure at a depth `h` in a liquid of density `rho` is plotted on the Y-axis and the value of `h` on the X-axis the graph is a strainght line. The slope of the straight line is `(g=` acceleration due to gravity)A. `rhog`B. `(1)/(rhog)`C. `(rho)/(g)`D. `(g)/(rho)` |
| Answer» Correct Answer - A | |
| 23. |
A liquid of density `rho` is filled in a vessel up to height H and a hole of cross section area A is made at a depth h below the free surface of liquid. The speed of liquid coming out of the hole is independent ofA. hB. aC. `rho`D. g |
| Answer» Correct Answer - C | |
| 24. |
The absolute pressure at a depth h below the surface of a liquid of density `rho` is [Given `P_(a)` = atmospheric pressure, g = acceleration due to gravity]A. `rho gh`B. `P_(a) + rho gh `C. `P_(a) - rho gh`D. `P_(a) 2 rho g h` |
| Answer» Correct Answer - B | |
| 25. |
The pressure at depth h below the surface of a liquid of density `rho` open to the atmosphere isA. greater than the atmospheric pressure by `rhogh`B. less than the atmospheric pressure by `rhogh`C. equal to the atmospheric pressureD. increases exponentially with depth |
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Answer» Correct Answer - A The pressure at depth h below the surface of a liquid of density `rho` open to the atmosphere is `P=P_(a)+rhogh` where `P_(a)` is the atmosphere pressure. Thus, pressure P at depth h below the surface of a liquid open to the atmosphere is greater than the atmospheric pressure by an amount `rhogh`. |
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| 26. |
The force acting on a window of are 50`xx`50 cm of a submarine at a depth of 2000 m in an ocean ,the interior of which is maintained at sea level atmospheric pressure is (density of sea water = `10 ^(3) kg m^(-3)` ,g =`10 m s^(-2)` )A. `5 xx10^(5)N`B. `25 xx10^(5)` NC. `5 xx 10^(6)`ND. `25 xx 10^(6)`N |
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Answer» Correct Answer - C Here, h=2000 m, `rho=10^(3) kg m^(-3), g=10 m s^(-2)` The pressure outside the submarine is `P=P_(a)+rhogh` where `P_(a)` is the atmospheric pressure. Pressure inside the submarine is `P_(a)` . Hence, net pressure acting on the window is gauge pressure. Gauge pressure, `P_(g)=P-P_(a)=rhogh` `=10^(3) kg m^(-3) xx 10 m s^(-2)xx 2000 m=2xx10^(7)` Pa Area of a window is `A=50 cm xx50 cm = 2500 xx 10^(-4) m^(2)` Force acting on the window is `F=P_(g)A` `=2xx10^(7)Pa xx 2500xx10^(-4) m^(2)=5xx10^(6)N` |
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| 27. |
A horizontal plate `(10cmxx10cm)` moves on a layer of oil of thickness 4 mm with constant speed of `10(cm)/(s)`. The coefficient of viscosity of oil is 4 poise. The tangential force applied on the plate to maintain the constant speed of the plate isA. `10^(3) `dyneB. `10^(4)` dyneC. `10^(5)` dyneD. none of these |
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Answer» Correct Answer - B Since plate moves with constant velocity `:.` viscous force `=` Applied force `etaA(Deltav)/(Deltax)=F`. |
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| 28. |
A metal plate of area `10^(-2)m^(2)` is placed on a liquid layer of thickness `2xx10^(-3)m`. If the liquid has coefficient of viscosity 2 S.I. units the force required to move the plate with a velocity of `3(cm)/(s)` isA. 0.3 NB. 0.03 NC. 3 ND. 30 N |
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Answer» Correct Answer - 1 `F=etaA(dv)/(dx)` |
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| 29. |
Between a plate of area `100 cm^(2)` and another plate of area `100 m^(2)` there is a `1 mm`, thick layer of water, if the coefficient of viscosity of water is `0.01` poise, then the force required to move the smaller plate with a velocity `10 cms^(-1)` with reference to large plate isA. 100 dyneB. `10^(4) `dyneC. `10^(6)` dyneD. `10^(9)` dyne |
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Answer» Correct Answer - A `F=etaA(dv)/(dx)` Where `A=100cm^(2),(dv)/(dx)=(10(cm)/(s))/(1mm)=100s^(-2)` |
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| 30. |
A metal ball `B_(1)` (density `3.2g//"cc")` is dropped in water, while another metal ball `B_(2)` (density `6.0g//"cc")` is dropped in a liquid of density `1.6g//"cc"`. If both the balls have the same diameter and attain the same terminal velocity, the ratio of viscosity of water to that of the liquid isA. 2B. 0.5C. 4D. indeterminate due to insufficient data |
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Answer» Correct Answer - B The terminal velocity of the bodyof radius r, density `rho` falling through a medium of density `alpha` is given by `v=2/9(r^(2)(rho-sigma_(water)g))/(eta)` where `eta` is the coefficient of viscosity of the medium `thereforevB_(1)=2/9(r_(B_(1))^(2))/(eta_("liquid"))(rho_(B_(2))sigma_("water"))g" "..(i)` and `v_(B_(2))=(2)/(9)(r_(B_(1))^(2))/(eta_("liquid"))(rhoB_(2)-sigma_("liquid"))g" "...(ii)` where the subscripts `B_(1)` and `B_(2)` respectively. `because r_(B_(1))=r_(B_(2)) and v_(B_(1))=v_(B_(2))" "` (Given) Substituting these values in (i) and (ii), we get `(eta_("water"))/(eta_("liquid"))=((rho_(B_(1))-sigma_("water")))/((rho_(B_(2))-sigma_("liquid")))` Substituting the given values, we get `(eta_("water"))/(eta_("liquid"))=((3.2-1))/((6.0-1.6))(because` Density of water `=1 g cm^(-3))` `(2.2)/(4.4)=0.5` |
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| 31. |
Water rises in a capillary tube to a height of 2.0cm. In another capillary tube whose radius is one third of it, how much the water will rise?A. 60 mmB. 80 mmC. 40 mmD. 30 mm |
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Answer» Correct Answer - A `hprop(1)/(r)` |
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| 32. |
A capillary tube of radius r is immersed in water and water rises in to a height h. The mass of water in the capillary tube is 5g. Another capillary tube of radius 2 r is immersed in water. The mass of water that will rise in this tube isA. mB. 2mC. `(m)/(2)`D. `4m` |
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Answer» Correct Answer - 2 `mpropr(becausemg=2pirTcostheta)` |
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| 33. |
A conical glass capillary tube of length 0.1 m has diameter `10^(-3)` and `5xx10^(-4)`m respectively at its ends. When it is just immersed in a liquid at `0^(@)C` with larger diameter in contact with liquid the liquid rises to `8xx10^(-2)` m in the tube. if another cylindrical glass capillary tube B is immersed in the same liquid at `0^(@)C` the liquid rises to `6xx10^(-2)` m height. The rise of liquid the tube B is only `5.5xx10^(-2)`m when the liquid is at `50^(@)C`. density of the liquid is `((1)/(14))xx10^(4)(kg)/(m^(3))` and angle of contact is zero. Effect of temperature on the density of the liquid and glass is negligible. The rate at which the surface tension changes with temperatrure considering the change to be linear is given by `-1.4xx10^(-n)(N)/(m^(@)C`. what is the value of n? |
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Answer» Correct Answer - 4 In tube A, the radius of capillary tube `r=r_(2)-((r_(2)-r_(1))/(l))xxh,T_(0)=(hrrhog)/(2)` `(DeltaT)/(Deltatheta)=(T_(50)-T_(0))/(Deltatheta)=(7.7xx10^(-2)-8.4xx10^(-2))/(50)` `=-1.4xx10^(-4)(N)/(m^(@)C)` `=-1.4xx10^(-n)(N)/(m^(@)C)` (given) Hence `n=4` |
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| 34. |
A capillary tube is immersed vertically in water such that the height of liquid column is found to be `x` on the surface of the earth. When it is taken to mine the capillary rise is `y` if `R` is the radius of the earth. Then the depth of mine isA. `d=R((y-x))/(x)`B. `d=R((y-x))/(y)`C. `d=R((x)/(y-x))`D. `d=R((y)/(y-x))` |
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Answer» Correct Answer - B `g^(1)=g((1-d)/(R))` |
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| 35. |
A long capillary tube of radius 1 mm, open at both ends is filled with water and placed vertically. What will be the height of water column left in the capillary ? (Surface tension of water is `73.5xx10^(-3)Nm^(-1))`A. 0.3 cmB. 3 cmC. 6 cmD. 0.03 cm |
| Answer» `pir^(2)hdg=2xx2pirTcosthetaimpliesh=(4T)/(rdg)` | |
| 36. |
Find the viscous drag between the two liquid layers each of area 100 `cm^(2)`, and having relative velocity 8 cm `s^(-1)`. The viscosity of the liquid is 0.004 PI and the layers are separated by a distance 4 cm. |
| Answer» Correct Answer - `8 xx 10^(-5)` N | |
| 37. |
If the terminal speed of a sphere of gold (density `=19.5kg//m^3`) is `0.2m//s` in a viscous liquid (density `=1.5kg//m^3`), find the terminal speed of a sphere of silver (density `=10.5kg//m^3`) of the same size in the same liquidA. `0.2(m)/(s)`B. `0.4(m)/(s)`C. `0.133(m)/(s)`D. `0.1(m)/(s)` |
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Answer» Correct Answer - D Terminal velocity of spherical body in a viscous liquid is given by, `v_(T)=(2r^(2))/(9eta)(rho-sigma)g` Where `r=` radius of the sphere `rho=` density of the sphere `eta=` coefficient of viscosity, `sigma=` density of liquid. `:. vprop(rho-sigma)` `(v_(g))/(v_(s))=(rho_(g)-sigma)/(rho_(s)-sigma)=(19.5-1.5)/(10.5-1.5)=2` `:. v_(s)=(v_(g))/(2)=(0.2)/(2)=0.1(m)/(s)` |
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| 38. |
A cylindrical vessel of area of cross-section A and filled with liquid to a height of `h_(1)` has a capillary tube of length l and radius r protuding horizontally at its bottom. If the viscosity of liquyid is `eta` and density `rho`. Find the time in which the level of water in the vessel falls to `h_(2)`.A. `(8etalA)/(pirhogr^(4))` ln `(h_(1))/(h_(2))`B. `(8etalA)/(pirhogr^(4))`C. `(etaA)/(g)(sqrt(h_(1))-sqrt(h_(2)))`D. `(8etalA)/(pirhogr^(4))` ln `(h_(2))/(h_(1))` |
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Answer» Correct Answer - A Let `h` be the height of water level in the vessel at instant `t` which decreases by dh in time dt. `:.` rate of flow of water through the capillary tube, `V=-A((dh)/(dt))` ….(1) Further, the rate of flow from poiseuille formula `V=(piPr^(4))/(8etal)` ....(2) The hyddrostatic pressure at depth h is `P=rhogh` from eqns (1) and (2) we have `-A(dh)/(dt)=(pirhohr^(4))/(8etal)` `dt=-(8etalA)/(pirhor^(4))(dh)/(h),t=(-8etalA)/(pirhogr^(4))int_(h_(1))^(h_(2))(dh)/(h)` |
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| 39. |
Two metal ball of radius R and 2 R falling through a fluid have same velocity at some point. The viscous drag acting on them at that instant are in the ratioA. `1 : 2`B. `1 : 4`C. `1 : sqrt(2)`D. `sqrt(2) : 1` |
| Answer» Correct Answer - A | |
| 40. |
After terminal velocity is reached the acceleration of a body falling through a viscous fluid is:A. zeroB. equal to gC. less than gD. more than g |
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Answer» Correct Answer - A When a falling body attains terminals velocity its acceleration becomes zero. |
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| 41. |
The terminal velocity of small sized spherical body of radius r falling vertically in a viscous liquid is given by the following proportionalityA. `(1)/(r^(2))`B. `r^(2)`C. `1/r`D. r |
| Answer» Correct Answer - B | |
| 42. |
When a drop of liquid splits upto a number of drops,A. Volume increases and energy is liberatedB. Area increases and energy liberatedC. Area decreases and energy is absorbedD. Area increases and energy is absorbed |
| Answer» Correct Answer - D | |
| 43. |
If Q is the rate of flow of liquid through a capillary tube of length l and radius r at constant pressure P, then the rate of flow of liquid through a capillary head isA. `(Q)/(162)`B. `(Q)/(32)`C. `(Q)/(64)`D. `(Q)/(81)` |
| Answer» Correct Answer - A | |
| 44. |
Water flows through a capillary tube at the rate of 10 cc per minute. If the pressure difference across the same tube is doubled, the rate of flow of water throught he tube wil be (in cc per minute)A. 20B. 5C. 40D. 2.5 |
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Answer» Correct Answer - 1 `Q=(piPr^(4))/(8etal),QalphaP` |
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| 45. |
The velocity distribution curve of the stream line flow of a liquid advancing through a capillary tube isA. circularB. ellipticalC. parabolicD. a straight line |
| Answer» Correct Answer - C | |
| 46. |
An iar tight container having a lid with negli-gible mass and an area of `8cm^(2)` is partially evacuated. If a 48 N forces is required to pull the lig of the container and the atmospheric pressure is `1.0xx10^(5)Pa` the pressure in the container before it is opened must beA. 0.6 atmB. 0.5 atmC. 0.4 atmD. 0.2 atm |
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Answer» Correct Answer - C `P_(1)-P_(2)=(F)/(A),P_(atm)-P_("in")=(F)/(A)` |
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| 47. |
A liquid is under stream lined motion through a horizontal pipe of non uniform cross section. If the volume rate of flow at cross section `a` is V, the volume rate of flow at cross section `(a)/(2)` isA. `(V)/(2)`B. `2V`C. `(V)/(4)`D. `V` |
| Answer» Correct Answer - D | |
| 48. |
A stream-lined body falls through air from a height `h` on the surface of a liquid . Let `d` and `D` denote the densities of the materials of the body and the liquid respectively, if `D gt d`, then the time after which the body will be intantaneously at rest, is:A. `sqrt((2h)/(g))`B. `sqrt((2h)/(g)(D)/(d))`C. `sqrt((2h)/(g)(d)/(D))`D. `(d)/((D-d))sqrt((2h)/(g))` |
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Answer» Retardation `=` net weight/mass `=(F_(B)-mg)/(m)` `v=u+at` then calculate for value of time `t` `v=0,u=sqrt(2gh)` |
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| 49. |
When the value of Reynilds number is less, the predominant forces areA. viscous forcesB. inertial forcesC. surface tension forcesD. gravitational forces. |
| Answer» Correct Answer - A | |
| 50. |
If the flow is stream lined then Reynolds number is less thanA. 2000B. 3000C. 1000D. 4000 |
| Answer» Correct Answer - C | |