Tag: concept of pressure

Questions Related to concept of pressure

As the depth of a liquid increases, the pressure of liquid decreases.

  1. True

  2. False


Correct Option: B
Explanation:

 pressure at a point in a fluid is = $\rho gh $ where $\rho$ is the density of the liquid , h is the height or depth of the object from the surface , so pressure increases with increase in depth so given statement is false .

hence option (B) is correct .

76 cm of Hg pressure is equivalent to 76 pascal.

  1. True

  2. False


Correct Option: B
Explanation:

 1 atm = 1 pa = 76 cm of Hg 

hence given statement is false so option (B) is correct

Sideways pressure exerted by a liquid is called its lateral pressure.

  1. True

  2. False


Correct Option: A
Explanation:

Pressure exerted sideways is known as  lateral pressure  , hence the given statement is true so option (A) is correct

With the increase in the weight of an object the pressure:

  1. Increases

  2. Decreases

  3. Is not affected

  4. None of these


Correct Option: A
Explanation:

With the increase in the weight of an object the pressure increases because pressure is thrust per unit area.

The area of cross-section of the pump plunger and the press plunger of hydraulic press are $0.03 m^2$ and $9 m^2$ respectively. How much is the force acting on the pump plunger of the hydraulic press overcomes a load of 900 kgf?

  1. 2 kgf

  2. 3 kgf

  3. 4 kgf

  4. 5 kgf


Correct Option: B
Explanation:

$Load=900 kgf, Effort (E)=?$
Area of cross section of the press plunger $=a _1=9 m^2$
Area of cross - section of the pump plunger $=a _2=0.03 m^2$
By Pascal's law,
Pressure exerted by pump plunger $=$ pressure exerted on press plunger.
i.e., $\displaystyle \frac {L}{E}=\frac {a _1}{a _2}\Rightarrow \frac {900 kgf}{E}=\frac {9 m^2}{0.03 m^2}$
$\displaystyle \Rightarrow E=\frac {900 kgf\times 0.03 m^2}{9 m^2}=3 kgf$.

Force exerted by a truck is 500000 N and the pressure on the ground is 2500000 Pa. Calculate the area of contact of tyres with ground?

  1. $0.1m^2$

  2. $0.2m^2$

  3. $0.3m^2$

  4. $0.4m^2$


Correct Option: B
Explanation:

Force $(F)=500000 N$
$Pressure=250000 Pa, Area (A)=?$
$A=\frac {F}{P}=\frac {500000}{2500000}m^2=0.2m^2$.

Deep sea divers put on special suit to :

  1. Maintain their body temperature in cold sea water

  2. Protect against sea animals

  3. Maintain pressure

  4. Keep them dry


Correct Option: C
Explanation:

To maintain normal atmospheric pressure below sealevel, deep seadivers wear a special suit.

Which of the following quantity is expressed as force per unit area?

  1. Work

  2. Pressure

  3. Volume

  4. Area


Correct Option: B
Explanation:

Pressure is expressed as force per unit area

Pressure is vector quantity .State true or false.

  1. True

  2. False


Correct Option: B
Explanation:

Pressure is a scalar quantity, not a vector quantity. It has a magnitude but no direction associated with it. Pressure acts in all directions at a point inside a gas. At the surface of a gas, the pressure force acts perpendicular to the surface.

For example. one that does not appear to move or flow. While the gas as a whole does not appear to move, the individual molecules of the gas, which we cannot see, are in constant random motion. Because we are dealing with a nearly infinite number of molecules and because the motion of the individual molecules is random in every direction, we do not detect any motion. If we enclose the gas within a container, we detect a pressure in the gas from the molecules colliding with the walls of our container. We can put the walls of our container anywhere inside the gas, and the force per area (the pressure) is the same. We can shrink the size of our "container" down to an infinitely small point, and the pressure has a single value at that point.

Therefore, it is false. 

Two stretched remembrance of area $2$ and $3\ m^{2}$ are placed in a liquid at the same depth. The ratio of the pressure on them is

  1. $1:1$

  2. $2:3$

  3. $\sqrt {2}:\sqrt {3}$

  4. $2^{2}:3^{2}$


Correct Option: A