InterviewSolution
Saved Bookmarks
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.
| 51. |
A boat having a length of 3 m and breadth of 2 m is floating on a lake. The boat sinks by 1 cm when a man gets on it. The mass of the mas is:A. 60 KgB. 72 kgC. 12 kgD. 128 kg |
|
Answer» Correct Answer - A Volume of water displaced, `V=(3m)xx(2m)xx((1)/(100)m)=(6)/(100)m^3` Mass of man `=`mass of water displaced, `m=Vrho=((6)/(100)m^3)(1000(kg)/(m^3))=60kg` |
|
| 52. |
A person in a boat floating in a small pond throws an anchor overboard. Does the level of the pond rise, fall or remain the same? |
| Answer» The level of the pond falls. This is because the anchor displaces more water while in the boat. A floating object displaces a volume of water whose weight is equal to the weight of the object. A submerged objecct displaces a volume of water equal to the volume of the object. Because the density of anchor is greater than that of water, a volume of water that weighs the same as the anchor will be greater than the volume of the anchor. | |
| 53. |
A glass of water has an ice cube floating in water. The water level just touches the rim of the glass. Will the water overflow when the ice melts? |
| Answer» When ice floats in water, it displaces its own weight of water Let V be the volume of water displaced On melting the ice will form exactly this volume V of water and just fill up the spece which the ice displace. So when ice melts, there will be no change in the level of water in the tumbler. | |
| 54. |
The density of salty solution of water as compared to density of pure water is:A. moreB. lessC. sameD. dependent on the concentration of the salty solution. |
| Answer» Correct Answer - A | |
| 55. |
A cube 8.5 cm on each side has a mass of 0.65 kg. Will the cube float or sink in water? Prove your answer. |
|
Answer» Volume of the cube, `V=(8.5cm)^3=614cm^3=6144xx10^-6m^3` Weight of water displaced by the cube when fully immersed in water, `F_B=Vrhog=(614xx10^-6m^3)(10^3(kg)/(m^3))(9.8(m)/(s^2))=6N` Weight of the cube, `W=0.65kgwt=0.65xx9.8=6.37N` Since `WgtF_B`, The cube will sink. |
|
| 56. |
If each side of a cube becomes n times, its volume becomes:A. 3 N times `n^2` timesB. `n^3` timesC. `3n^3` times.D. |
| Answer» Correct Answer - C | |
| 57. |
A piece of copper of mass 106 g is dipped in a measuring cylinder containing water at 22 ml mark. The water rises to 34 ml mark. Find (a) volume of the copper piece (b) the density of copper. |
|
Answer» (a) Volume of the copper piece,`V=34ml-22ml` `=12ml` `=12cm^3` (b) Density of copper, `d=("mass of copper piece"(M))/("volume of copper piece"(V))` `=(160g)/(12cm^3)=8.83(g)/(cm^2)` `=8.83xx1000(kg)/(m^3)` `=883(kg)/(m^3)` |
|
| 58. |
When each side of a regular body is doubled, its volume bacomes:A. two timesB. four timesC. eight timesD. sixteen times |
| Answer» Correct Answer - C | |
| 59. |
Find the least count of the measuring cylinder used and the volume of the sphere in the set-up shown in fig. |
|
Answer» Least cound of measuring cylinder `=(2mL-1mL)/(5" divisions")=0.2mL` Volume of solid `=` final reading of measuring cylinder - initial reading of measuring cylinder `=8.2mL-6mL` `=2.2mL` |
|
| 60. |
`1m^3` is equal to :A. `10^3cm^3`B. `10^4cm^3`C. `10^6cm^3`D. `10^@cm^3` |
| Answer» Correct Answer - C | |
| 61. |
A piece of iron of density `7.8xx10^-3(kg)/(m^3)` and volume `100cm^3` is totally immersed in water. Calculate (a) the weight of the iron piece in air (b) the upthrust and (c ) apparent weight in water. |
|
Answer» (a) Here, density of iron,`d=7.8xx10^-3(kg)/(m^3)` volume of iron piece, `V=100cm^3=100xx10^-6m^3=10^-3m^3` mass of iron piece, `M=Vxxd=(10^-4m^3)xx(7.8xx10^-3(kg)/(m^3))=0.78kg` Weight of iron piece, `W=Mg=(0.78kg)(10(m)/(s^2))=7.8N` (b) Upthrust, `F_B=` weight of water displaced `=` volume of water displaced `xx` density of water `xxg` `=`volume of iron piece `xx` density of water `xxg` `=(10^-4m^3)(1000(kg)/(m^3))(10(m)/(s^2)=1N` (c ) Apparent weight `=` true weight of iron piece`-`upthrust on iron piece in water `=W-F_B=7.8N-1N` `=6.8N` |
|
| 62. |
When a body is fully immersed in a liquid, the apparent loss in its weght is:A. equal to the weight of the liquid displacedB. more than the weight of the liquid desplacedC. less than the weight of the liquid displacedD. depends upon the manner in which the body is immersed in the liquid. |
| Answer» Correct Answer - A | |
| 63. |
Two different object are completely immersed in water and undergo same loss in weight. Is it necessary that the weights of these objects in air be also the same? |
| Answer» The loss in weight of an object when immersed in water depends on its volume. Thus, two objects with equal volumes have the same loss of weight.. But their own weights depend on their densities. In case, their densities are different, their weights in air will be different. For example, cork ball and a steel ball of the same size undergo the same loss in weight in water but these two have differents weights in air. | |
| 64. |
The volume of 500 g sealed packet is 350 `cm^3`. Will the packet float or sink if the density of water is `1(g)/(cm^3)`? What will be the mass of the water displaced by this packed? |
|
Answer» Here, Mass of packet, `M=500g` volume of the packet, `V=350cm^3` Clearly, density of packet, `d=(M)/(V)=(500)/(350)=1.428(g)/(cm^3)` Since the density of packet is more than density of water the packet will sink. As the packet is fully submerged in water, mass of water displaced by the packet`=`volume of the packet`xx`density of water `=(350cm^3)xx(1(g)/(cm^3))` `=350g` |
|
| 65. |
The volume of 50 g of a substance is 20 `cm^3`. If the density of water is `1(g)/(cm^3)`, will the substance float or sink? |
|
Answer» Here, Mass of the substance`M=50g` volume of the substance, `V=20cm^3` Clearly, density of the substance, `d=(M)/(V)=(50g)/(20cm^3)=2.5(g)/(cm^3)` Since density of substance `(2.5(g)/(cm^3)`) is more than that of water `(1(g)/(cm^3))`, the substance will sink. |
|
| 66. |
The mass of a block made of certain material is `13.5 kg` and its volume is `15 xx 10^-3 m^3`. Will the block sink or float in water ? Give a reason for your answer. |
|
Answer» `M=13.5kg`,`V=15xx10^-3m^3`. Density of the block, `d=(M)/(V)=(13.5kg)/(15xx10^-3m^3)=0.9xx10^3(kg)/(m^3)=900(kg)/(m^3)` The block floats since its density isless than that of water, i.e., `1000(kg)/(m^3)`. |
|
| 67. |
The density of a substance is defined as:A. density `=`volume/massB. density`=`volume/`(mass)^2`C. density`=`mass/volumeD. density`=(volume)^2`/mass. |
| Answer» Correct Answer - C | |
| 68. |
`1m^3` is equal to :A. 1 litre (L)B. 10 LC. 1000 LD. 100 L. |
| Answer» Correct Answer - C | |
| 69. |
The density of water is maximum at:A. `0^@C`B. `10^@C`C. `4^@C`D. `100^@C` |
| Answer» Correct Answer - C | |
| 70. |
Loss of wuight of a body immersed in a liquid is:A. equal to the weight of the liquid displacedB. more than the weight of the liquid displacedC. less than the weight of the liquid displacedD. zero |
|
Answer» Correct Answer - A a |
|
| 71. |
How high would the water column have been in Q. 3? |
| Answer» As `h_wrho_wg=h_mrho_mg`,`h_w=(h_mrho_m)/(rho_w)=(76cm)(13.6)=1034cm=10m` | |
| 72. |
What is the density of water at `20^@C` in SI units? |
| Answer» `1000(kg)/(m^3)`. | |
| 73. |
The SI unit of density is:A. `(kg)/(m)`B. `(kg)/(m^2)`C. `(kg)/(m^3)`D. `kg` |
| Answer» Correct Answer - C | |
| 74. |
A solid body of mass 150 g and volume 250 `cm^3` is put in water. Will the body float or sink? |
|
Answer» Here, mass of the body, `M=150g` volume of the body, `V=250cm^3` density of the body, `d=(M)/(V)=(150g)/(250cm^3))` `=0.6(g)/(cm^3)` Since the density of the body `(0.6(g)/(cm^3)`) is less than the density of water `(1(g)/(cm^3)`), the body will float on water. |
|
| 75. |
The density of water at `4^@C` is:A. `1(kg)/(m^3)`B. `10(kg)/(m^3)`C. `1000(kg)/(m^3)`D. `100(kg)/(m^3)` |
| Answer» Correct Answer - C | |
| 76. |
The SI unit of volume is:A. litre (L)B. `L^3`C. `mL^3`D. `m^3` |
| Answer» Correct Answer - D | |
| 77. |
Air is a fluid and our bodies displace air. And so a buoyant force is acting on each of us. Estimate the magnitude of the buoyant force on a 75 kg person due to air displaces. Is the actual weght of the person more or less than the scale reading? |
|
Answer» Volume of person, `V_p=(m)/(rho_p)=(75kg)/(1000(kg)/(m^3))=0.075m^3` Buoyant force, `F_B=rho_agV_p=(1.29(kg)/(m^3))(9.8(m)/(s^2))(0.075m^3)=0.95N=1N` (as estimated density of person, `rho_p=1000(kg)/(m^3)`,density of air, `rho_a=1.29(kg)/(m^3)`) The weight of the person is `1N(=0.1kg)` more than the scale reading. |
|
| 78. |
Two blocks of equal bolume, one of iron and one of aluminium, are dropped into a body of water. Which block will experience the greater buoyant force? Why? |
| Answer» Same buoyant force, because buoyant force on the object depends on the volume of fluid displaced by it and is independent of its mass. | |
| 79. |
The SI unit of relative density is:A. `(kg)/(m^3)`B. `(kg)/(m)`C. `(kg)/(m^2)`D. no limit |
| Answer» Correct Answer - D | |
| 80. |
Name two factors on which the buoyant force acting on an object depends. |
| Answer» (a) Volume of the object immersed in the liquid. (b) density of the fluid in which the object is immersed. | |
| 81. |
A body floats in a liquid if the buoyant force isA. zeroB. greater than its weightC. less than its weightD. equal to its weight |
|
Answer» Correct Answer - D d |
|
| 82. |
In what direction does the buoyant force on an object immersed in a liquid act? |
| Answer» The buoyant force on an object immersed in a liquid always acts vertically upwards i.e., in a direction opposite to the weight of the object. | |
| 83. |
Where does a solid weigh more: in air or in a liquid? |
| Answer» A solid weighs more in air than in a liquid. This is due to the reason that the buoyant force of the liquid on the solid is more than the buoyant force of the air on the solid. | |
| 84. |
The relative density of mercury is 13.6 what does this statement mean? |
| Answer» This statement means that mercury is 13.6 times denser than water and its density is `13.6xx10^3(kg)/(m^3)` | |
| 85. |
The density of turpentine oil is `840(kg)/(m^3)`. What will be its relative density? |
| Answer» Relative density of turpentine oil`=("density of tupentine oil")/("density of water at " 4^@C)=((840kg)/(m^3))/((1000kg)/(m^3))=0.84` | |
| 86. |
Air is a fluid and our bodies displace air. As a result of this, a buoyant force is acting on each one of us. What is the approximate density of your body? |
| Answer» Since most people can barely float in water, density of human body is about the density of water, i.e., `rho=1000(kg)/(m^3)` | |
| 87. |
Lead has greater density than iron and both are denser than water. Is the buoyant force on a lead object greater than, less than or equal to the buoyant force on an iron object of the same volume? |
| Answer» The buoyant force of a liquid on an object is equal to the weight of the liquid displaced by it. Since the lead object and the iron object have the same volume, both of them displace the same amount of water, Hence, the buoyant force on both the objects is the same. | |
| 88. |
An object weighs 9.8 N in air and 9.0 N when fully immersed in water. How much is the buoyant force on the object? |
| Answer» Buoyant force on the object`=`weight of the object in air`-`weight of the object when fully immersed I water `=9.8N-9.0N=0.8N` | |
| 89. |
What is the relationship between the buoyant force on an object and the liquid displaced by it? |
| Answer» Buoyant force on an object`=`weight of the liquid displaced by the object. | |
| 90. |
A body of 2.0 kg floats in a liquid. What is the buoyant force on the body? |
| Answer» `F_B=W=mg=(2.0kg)(10(m)/(s^2))=20N` | |
| 91. |
Calculate the mass of a body whose volume is `2m^3` and relative density is 0.52. |
|
Answer» Density of the body, `d=`relative density of the body`xx` density of water at `4^@C` `=0.52xx1000(kg)/(m^3)=520(kg)/(m^3)` Mass of the body, `M=Vd=(2m^3)xx(520(kg)/(m^3))=1040kg` |
|
| 92. |
The mass of a density bottle is 25 g when empty, 50 g when filled completely with water and 365 g when filled completely with mercury. Find the density of mercury. |
|
Answer» mass of water`=50g-25g=25g` mass of an equal volume of mercury`=365g-25g=340g` Relative density of mercury`=(340g)/(24g)=13.6` density of mercury`=13.6xx`density of water (at`4^@`C) `13.6xx1000(kg)/(m^3)=13600(kg)/(m^3)` |
|
| 93. |
State one important effect produced by the buoyant force exerted by water. |
| Answer» An object appears to weigh less when submerged in water than when it is in air. | |
| 94. |
The pressure due to atmoshere is `1-013xx10^5` Pa. Find the force exerted by the atmosphere on the top surface of a table 2-0 m long and 1-0m wide. |
|
Answer» Here, pressure dur to the atmosphere,`P=1.013xx10^5Pa=1.013xx10^5(N)/(m^2)` area on which atmospheric pressure acts, `A=2.0mxx1.0m=2.0m^2` Thus, force exerted by the atmosphere, `F=PA=(1.013xx10^5(N)/(m^2))xx(2.0m^2)` `=2.026xx10^5`N |
|
| 95. |
(a) Whi are wide wooden sleepers kept below railway lines? (b) Whi does a balloon not collapse under atmospheric pressure? |
|
Answer» (a) To reduce pressure on the railway lines and to prevent them from sinking into ground. (b) Because the pressure of the gas inside the balloon balances the atmospheric pressure. |
|
| 96. |
Explain why a wide steel belt is provided over the wheels of an army tank. |
| Answer» Since `P=(F)/(A)`, the wide belt (large area A) over the wheels of an army tank reduces the pressure (P) exerted by the tank on the ground due to its weight (F) and this prevents the tank from sinking into the dround. | |
| 97. |
What force acting on an area of `0.5 m^2` will produce a pressure of 500 Pa ? |
| Answer» As `P=(F)/(A)`,`F=PA=(500Pa)(0.5m^2)=250N`. | |
| 98. |
Explain how do we breath (inhalation and exhalation). |
| Answer» To inhale the lungs physically expand the internal pressure decreases, and air flows into lungs. To exhale, the lungs contract, the internal pressure increases and the air is forced out of lungs. | |
| 99. |
Using a spring balance, a given solid is weghed in the air. It is then weghed by immersing fully in water in each of the three vessels containing water as shown in fig. The apparent weight of the solid will be: A. least in AB. least in BC. least in CD. equal in all |
|
Answer» Correct Answer - D Buoyancy on the solid is independent of the shape of the vessel in which it is immersed. |
|
| 100. |
You find your mass to be 42 kg on a weighing machine. If your mass more or less than 42 Kg? |
| Answer» In fact, a weighing machine is a sort of spring balance which measures the weight (and not the mass) of a body. When we stand on the weighing machine, our weight (which is due to gravitational attraction of the Earth) acts vertically downwards. But the buoyancy due to air on our body acts vertically upwards. As a result of this, our apparent weight (true weight-buoyant force) is less than the true weight. Since the weighing machine measures the apparent weight, our true weight is more, i.e., more than 42 kg. | |