Tag: introduction to pressure

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Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

Calculate the vertical height of a mercury column which exerts a pressure of 81600 Pa. (Density of mercury is $13.6 g cm^{-3}$ and $g=10 ms^{-2})$.

  1. 0.2 m

  2. 0.4 m

  3. 0.6 m

  4. 0.8 m
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$Pressure (P)=81600 Pa$
$Density (d)=13.6 g cm^{-3}$
$=13.6\times 1000 kg m^{-3}$
$(\therefore 1 g cm^{-3}=1000 kg m^{-3})$

Acceleration due to gravity $(g)=10 ms^{-2}$
$P=hdg$
$\Rightarrow h=\dfrac {P}{dg}=\dfrac {81600}{13.6\times 1000\times 10}$
$\Rightarrow h=0.6 m$
Therefore, vertical height of mercury column is 0.6 m.

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

A liquid of density $12 kg m^{-3}$ exerts a pressure of 600 Pa at a point inside a liquid. What is height of liquid column above that point? $[g=10 ms^{-2}]$

  1. 4 m

  2. 5 m

  3. 6 m

  4. 7 m
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Denstiy = 12 kg m^{-3}, Pressure=600 Pa$
$Pressure=hdg$
$\Rightarrow hdg=Pressure\Rightarrow height=\dfrac {P}{dg}$
$=\dfrac {600}{12\times 10}m=5m.$

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

A metal cube is placed in an empty vessel. When water is filled in the vessel so that  cube is completely immersed in the water, the force on the bottom of the vessel in contact with the cube-

  1. Will increase

  2. Will decrease

  3. Will remain the same

  4. Will become zero
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to Archimedes' principle, the buoyant force acting on the cube is equal to the weight of the water displaced. Since the cube is resting on the bottom, the total downward force exerted on the bottom of the vessel remains the same because the weight of the water added is balanced by the buoyant force pushing up on the cube.

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

A tank filled with water is placed in vacuum. The net pressure at point which is $10 m$ below the surface of water will be $(g = 10 m/s^2)$

  1. $100 \ kPa$
  2. $10 \ kPa$
  3. $1 \ kPa$

  4. Zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a vacuum, there is no atmospheric pressure acting on the surface of the water. The pressure at a depth h is given by P = rho * g * h. Here, rho = 1000 kg/m^3, g = 10 m/s^2, and h = 10 m, so P = 1000 * 10 * 10 = 100,000 Pa = 100 kPa.

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure
A fluid exert pressure 

  1. only downwards

  2. only upwards

  3. in all directions

  4. Fluids do not exert pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A fluid is a substance that has no fixed shape and yields easily to external pressure; a gas or  a liquid.

Pressure is exerted by fluids because of their weight. Static fluid pressure is exerted by the depth of the fluid, the density of the fluid and the acceleration of gravity. They exert pressure in all directions, which is given by $F=PA$
where $P$ is the pressure, and $A$ is the area on which force acts.

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure
Which of the following can exert pressure

  1. Solids

  2. Liquids

  3. Gases

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A fluid is a substance that has no fixed shape and yields easily to external pressure; a gas or  a liquid.

Pressure is exerted by fluids because of their weight. Static fluid pressure is exerted by the depth of the fluid, the density of the fluid and the acceleration of gravity.
Well knowingly, the solids exert pressure on the surface on which they are placed, given by $P=\dfrac{mg}{A}$
Hence correct answer is option D.

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

Which of the following is true?

  1. Fluid do not have any weight

  2. Only liquids have weight

  3. Only gases have weight

  4. Fluids have weight
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A fluid is a substance that has no fixed shape and yields easily to external pressure; a gas or  a liquid.

Pressure is exerted by fluids because of their weight. Static fluid pressure is exerted by the depth of the fluid, the density of the fluid and the acceleration of gravity.

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

Two stretched membranes of area $2 cm^2$ and $3 cm^2$ are placed in a liquid at the same depth. The ratio of the pressure on them is :

  1. $1 : 1$
  2. $2 : 3$
  3. $3 : 2$
  4. $2^2 : 3^2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

pressure depends on depth not on area so the two stretched membrane would  have  equal pressure.

so ratio of their pressures would be 1 : 1.
hence option (A) is correct

Multiple choice physics forces and matter pressure in fluids pressure in liquids introduction to pressure

Fill in the blank

Fluids at a given depth exert ______ pressure in all directions 

  1. same

  2. independent

  3. different

  4. zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fluids at a given depth exert same pressure in all directions.
Pressure of a liquid is directly proportional to the depth, and for a given depth the liquid exerts the same pressure in all directions according to Pascal's law.