NEET Physics Pressure Density Pascals Law and Archimedes Principle Online Test Set A

1. Assertion : Imagine holding two identical bricks under water. Brick A is completely submerged just below the surface of water, while Brick B is at a greater depth. The magnitude of force exerted by the person (on the brick) to hold brick B in place is the same as magnitude of force exerted by the person (on the brick) to hold brick A in place.
Reason : The magnitude of buoyant force on a brick completely submerged in water is equal to magnitude of weight of water it displaces and does not depend on depth of brick in water.

2. A cone full of water, is placed on its side on a horizontal table, the thrust on its base is x times the weight of the contained fluid, where 2a is the vertical angle of the cone. Find the value of x.

3. An iceberg is floating in ocean. What fraction of its volume is above the water ? (Given : density of ice = 900kg/m³ and density of ocean water = 10³⁰ kg/m³)

4. A vessel containing water is given a constant acceleration ‘a’ towards the right along a straight horizontal path. Which of the following diagrams represents the surface of the liquid ?

5. A sphere of solid material of specific gravity 8 has a concentric spherical cavity and just sinks in water. The ratio of radius of cavity to that of outer radius of the sphere must be

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7. A wooden block, with a coin placed on its top, floats in water as shown in fig. the distance l and h are shown there. After some time the coin falls into the water. Then

8. A boy can reduce the pressure in his lungs to 750 mm ofmercury. Using a straw he can drink water from a glass upto the maximum depth of (atmospheric pressure = 760 mm of mercury; density of mercury = 13.6 gcm^–3)

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11. The two thigh bones, each of cross-sectional area 10 cm² support the upper part of a human body of mass 40 kg. Estimate the average pressure sustained by the bones. Take g = 10 m/s²

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13. In rising from the bottom of a lake, to the top, the temperature of an air bubble remains unchanged, but its diameter gets doubled. If h is the barometric height (expressed in m of mercury of relative density r) at the surface of the lake, the depth of the lake is

14. A cubical box is to be constructed with iron sheets 1 mm in thickness. What can be the minimum value of the external edge so that the cube does not sink in water?

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16. A concrete sphere of radius R has a cavity of radius r which is packed with sawdust. The specific gravities of concrete and sawdust are respectively 2.4 and 0.3 for this sphere to float with its entire volume submerged under water. Ratio of mass of concrete to mass of sawdust will be

17. The force acting on a window of area 50 cm × 50 cm of a submarine at a depth of 2000 m in an ocean, interior of which is maintained at sea level atmospheric pressure is (Density of sea water = 10³ kgm^–3, g = 10 ms^–2)

18. Assertion: The apparent weight of a floating body is zero.
Reason: The weight of the block acting vertically downwards is balanced by the buoyant force acting on the block upwards.

19. In a hydraulic lift, compressed air exerts a force F₁ on a small piston having a radius of 5 cm. This pressure is transmitted to a second piston of radius 15 cm. If the mass of the load to be lifted is 1350 kg, find the value of F₁ ? The pressure necessary to accomplish this task is

20. A vessel contains oil (density = 0.8 gm/cm³) over mercury (density = 13.6 gm/cm³). A homogeneous sphere floats with half of its volume immersed in mercury and the other half in oil. The density of the material of the sphere in gm/cm³ is

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22. A block of ice floats on a liquid of density 1.2 in a beaker then level of liquid when ice completely melt

23. Consider an iceberg floating in sea water. The density of sea water is 1.03 g/cc and that of ice is 0.92 g/cc. The fraction of total volume of iceberg above the level of sea water is near by

24. Assertion: A small iron needle sinks in water while a large iron ship floats.
Reason: The shape of iron needle is like a flat surface while the shape of a ship is that which makes it easier to float.

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26. Specific gravity of a body is numerically equal to

27. A candle of diameter d is floating on a liquid in a cylindrical container of diameter D (D >> d) as shown in figure. If it is burning at the rate of 2 cm/hour then the top of the candle will

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29. The pressure at the bottom of a tank containing a liquid does not depend on

30. Pressure applied to enclosed fluid is

31. _________ and _________ play the same role in case of fluids as force and mass play in case of solids.

32. A vessel with water is placed on a weighing pan and it reads 600 g. Now a ball of mass 40 g and density 0.80 g cm^–3 is sunk into the water with a pin of negligible volume, as shown in figure keeping it sunk. The weighting pan will show a reading

33. According to archimedes' principle, loss of weight of a body immersed in a liquid is equal to

34. Hydraulic lifts and hydraulic brakes are based on

35. Liquid pressure depends upon