Explore topic-wise InterviewSolutions in .

A) P = P_o + hρg 

B) relative density

Relative density of liquids can be determined by using hydrometer.

D) Hydralic jack

C) Bramah press

B) Archimedes

Correct option is C) barometer

D) apparent loss of weight

D) density of iron is more than the density of wood

Pascal’s principle: 

External pressure applied to an enclosed body of fluid is transmitted equally in all directions throughout the fluid volume and the walls of the containing vessel. 

Use :

1.  This principle is used in designing and working of hydraulic jacks. 
2.  Hydraulic jacks are useful to lift heavy objects like cars and other vehicles in automobile work shops when the vehicles are to be required or repaired. 
3.  Here very less force is used to lift such heavy vehicles.

Appreciation :

1.  Hydraulic jacks are used not only in automobile work shops, but also in so many industries where heavy weights are to be lifted with a little force. 
2.  All the comforts which we are enjoying now are the efforts of scientists who discovered the laws and principles. 
3.  Hence we have to appreciate the efforts of Pascal for his contribution in designing these principles.

Archimedes’ principle states that when a body is immersed in a fluid it experiences an upward force of buoyancy equal to the weight of fluid displaced by the immersed portion of the body.

Hydraulic lift works using Pascal’s law.

Density of plastic is less than water. As the density of water is more than plastic, water exerts upward force which is known as buoyant force. So, the block of plastic come up to the surface of water.

Air pressure is the weight of air in the atmosphere above the reservoir (bowl of mercury). So, the level of mercury continues to change until the weight of mercury in the glass tube is exactly equal to the weight of the air above the reservoir, which is 76 cm.

D) Both B & C

The density of water is 1 gm/cc and that of milk is 1.02 gm/cc.

Hence milk is slightly denser than water.

Weight of water = 22 – 20 = 2 gm 

Weight of oil = 21.76 – 20 = 1.76 gm

Density of oil = Weight of the oil / Weight of the same volume of water

= 1.76 / 2 = 0.88 gm/cm³

Density : 

Density is defined as mass per unit volume.

 Density = \(\frac{Mass}{Volume}\)

Unit of density is gm/cm³ or kg/m³. 

Relative density : 

Relative density of an object is the ratio of density of the object to the density of water.

Relative density of an object =  Density of the object / Density of water 

(or)

Relative density of an object = Weight of the object / Weight of water equal to the volume of the object 

Value of density of water = 1 gm/cm³ (or) 1 kg/cm³.

a) Salt water is denser than freshwater. 

b) Buoyant force is the upward force only. The body is submerged means, its weight is more than the buoyant force. Here there will be no horizontal buoyant force. 

c) Buoyant force on iron block is more than that of aluminium block. 

d) It floats on higher depth than in the first case.

The relative density of wooden block is less than the relative density of water whereas relative density of marble (glass) is more than that of water. Hence wooden block floats on water and marble sinks in water.

Yes, the water level rises. 

Reason : 

The ice cube floats on water, because its density is less than the density of water. When ice cube melts, it becomes water, so that the water level rises.

Density of the substance = Mass / Volume = 50 / 20 = 2.5 g/cm³

Density of water = 1 gm/cm³

Density of the substance > Density of water 

Relative density of the substance = \(\frac{2.5\,gm/cm^3}{1\,gm/cm^3}\) = 2.5

Relative density of the substance = Weight of the substance / Weight of the water equal to the volume of the substance 

⇒ 2.5 = 50 / x 

⇒ x = 50 / 2.5 = 20 g

∴ Weight of the water displaced by the substance = 20 g

Yes, we can make iron to float on water. 

Procedure: 

1. Take a piece of iron and drop it in a vessel of water.
2. We observe that the iron piece sinks in water. 
3. Take a thin foil of iron and fold it into four folds. 
4. Drop it in water. It sinks.
5. Now unfold the foil and bend it in the form of a bowl. [You can use an iron tin also] 
6. Now drop the bowl in water. 
7. If floats on water.

Reason: 

The weight of water displaced by iron bowl (iron tin) is less than the weight of the iron bowl (iron tin).

Correct option is A) floats on

Correct option is D) buoyancy

Correct option is B) Pascal

The weight of water displaced by iron needle is less than its own weight, so it sinks. On the other hand, the ship displaces water more than its own weight, so it floats on water.

Given 

1. density = 19 g/cm³

2. Mass = 95 g

3. density = Mass / Volume 

4. Volume of gold = Mass / Density = 95g /19 g/cm³ 

Pascal’s principle states that external pressure applied to an enclosed body of fluid is transmitted equally in all directions throughout the fluid.

The body sinks in water. 

Reason : 

The combined mass of the system increases, so the combined density also increases. Hence the body sinks in water.

D) 1.01 × 10⁵ N/m²

Correct option is B) sinks

Correct option is A) 1.01 × 10⁵ 

Correct option is C) buoyancy

Correct option is B) buoyancy

• Suspend a stone from a spring balance. Note the reading of the spring balance. 
• Take a beaker half-filled with water. 
• Now immerse the stone in the water, note the reading of the spring balance. 
• We notice that the stone, when immersed appears to lose some weight. 
• The immersed stone appears to lose weight because the force of buoyancy.
• Thus the apparent loss of weight must be equal to the force of buoyancy acting on the immersed stone.

a) By Archimedes’ principles, the buoyant force acting on the object by it. So, the buoyant force on the boat = 6000 newtons. 

b) According to the principle of floating Weight of object = Weight of liquid displaced by it ⇒ Weight of the boat = 6000 newtons

• Suspend a stone from a spring balance. 
• Note that the reading of the spring balance. 
• The reading gives the weight of the stone. 
• Take a beaker half filled with water. 
• Now immerse the stone in the water. 
• Note the reading of the spring balance. 
• The reading gives the weight of the immersed stone. 
• We may notice that the stone, when immersed, appears to lose some weight. 
• The immersed stone appears to lose weight because the force of BUOYANCY, exerted on the stone by the water in the upward direction. 
• Thus the apparent loss of weight must be equal to the force of buoyancy acting on the immersed stone. 
• The lose of weight of stone is equal to weight of the water displaced by the stone, this is the force of buoyancy.

Pascal’s principle states that external pressure applied to an enclosed body of fluid is transmitted equally in all directions throughout the fluid volume and the walls of the containing vessel.

A) \(\cfrac{1}2\) (ρ₁ + ρ₂)

 B) \(\cfrac{p_1p_2}{p_1+p_2}\)

‘Heavy’ and ‘light’ can be decided based on the density of the object. Among the objects of equal volume, the one which weighs more can be treated as ‘heavy’ and the other one can be treated as ‘light’.

B) the density of the object is less than the density of the liquid

Correct option is D) No units

Correct option is C) kg/m³

Relative density of silver = 10.8

Relative density = Density of silver / Density of water

Density of water in S.I. system = 0³ kg/m³. 

Density of silver = Relative density × Density of water = 10.8 × 10³ kg/m³.

 C) \(\cfrac{weight\,of\,the\,liquid}{weight\,of\,same\,volume\,of\,water}\)

Correct option is D) no units