Tag: examples of hydraulic press

Questions Related to examples of hydraulic press

Two general types of vacuum assisted power brakes are

  1. Vacuum suspended and power suspended

  2. Integral and pressure suspended

  3. Atmospheric and vacuum suspended

  4. Power and pressure suspended


Correct Option: C
Explanation:

Atmospheric power brakes and vaccum suspended power brake are two classifications of vaccum assisted power brakes.

If the system is not in free fall, which of the following statements is true about hydrostatic pressure?

  1. In a liquid, point at different depth can never be at the same pressure.

  2. In a liquid, point at different depth may be at the same pressure.

  3. In different liquids, points at different depths can be at the same pressure.

  4. In different liquids, points at the same depths can never be at the same pressure.


Correct Option: A,C,D
Explanation:

pressure for same liquid is $\rho gh$

at same depth  pressure is same   as for specific liquid density is constant and depth is same 
 for different liquid 
pressure at different depth can be same as  $\rho h$ can be constant for different liquid 
but for different liquid pressure at same depth cannot be same as density is different and depth is same so pressure cannot be same

A hydraulic machine exerts a force of 900 N on a piston of diameter 1.80 cm. The output force is exerted on a piston of diameter 36 cm. What will be the output force?

  1. $12\times 10^4 N$

  2. $16\times 10^4 N$

  3. $36\times 10^4 N$

  4. $38\times 10^4 N$


Correct Option: C
Explanation:

$f=900 N$
$a=\pi \times (\frac {1.8}{2})^2=\pi \times \frac {(1.8)^2}{4}$
$A=\pi \times (\frac {36}{2})^2=\pi \times \frac {(36)^2}{4}$
Now $\frac {f}{a}=\frac {F}{A}$
$\Rightarrow \frac {900\times 4}{\pi (1.8)^2}=\frac {F\times 4}{\pi \times (36)^2}$
$\therefore F=\frac {900\times 4}{\pi \times 1.8\times 1.8}\times \frac {\pi \times 36\times 36}{4}$
$=36\times 10^4N$.

A U-tube is partially filled with water. Oil which does not mix with water is next poured into one side, until water rises by $25\;cm$ on the other side. If the density of oil is $0.8\;g/cc$, the oil level will stand higher than the water level by

  1. $6.25\;cm$

  2. $12.50\;cm$

  3. $18.75\;cm$

  4. $25.00\;cm$


Correct Option: B

The area of the piston in hydraulic machine are $10cm^2$ and $225cm^2$. The force required on the smaller piston to support a load of $1000N$ on the larger piston.

  1. 44.44 N

  2. 55.55 N

  3. 33.33 N

  4. 4.44 N


Correct Option: A
Explanation:

$\begin{array}{l} \dfrac { f }{ { 10 } } =\dfrac { { 1000 } }{ { 225 } }  \ f=\dfrac { { 10000 } }{ { 225 } }  \ f=44.44N \end{array}$

$ \therefore$ Option $A$ is correct.

Hydraulic machines work on the application of

  1. Pascal's law

  2. Newton's law

  3. Law of Gravity

  4. none of these


Correct Option: A
Explanation:

The hydraulic machine uses Pascal's principle, which states that states that the pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid.
The hydraulic machine is used to multiple force or to transmit force from one location to another. 
i)     hydraulic brakes
ii)    hydraulic press
ii)    hydraulic lift

What should be the ratio of area of cross section of the master cylinder and wheel cylinder of a hydraulic brake so that a force of $15  N$ can be obtained at each of its brake shoe by exerting a force of $0.5  N$ on the pedal?

  1. $1: 60$

  2. $1: 30$

  3. $1: 15$

  4. $1: 45$


Correct Option: B
Explanation:

We know that $P _{1} = P _{2}$

$\Rightarrow \dfrac{F _{1}}{A _{1}} = \dfrac{F _{2}}{A _{2}} $

$\Rightarrow \dfrac{A _{1}}{A _{2}} = \dfrac{F _{1}}{F _{2}}  = \dfrac{1}{30} $

$\Rightarrow  1:30 $

In a hydraulic lift, used at a service station the radius of the large and small piston are in the ratio of $20 : 1$. What weight placed on the small piston will be sufficient to lift a car of mass $1500 kg$ ?

  1. $3.75 kg$

  2. $37.5 kg$

  3. $7.5 kg$

  4. $75 kg$


Correct Option: A
Explanation:

Answer is A.

Pressure is the amount of force acting per unit area. That is, $P=F/A$.
where:
$p$ is the pressure,
$F$ is the normal force,
$A$ is the area of the surface on contact. Let us consider A = $\pi { r }^{ 2 }$.
Therefore, $\dfrac { { F } _{ 1 } }{ { \pi { r } _{ 1 } }^{ 2 } } =\dfrac { { F } _{ 2 } }{ { \pi { r } _{ 2 } }^{ 2 } } $.
In this case, $\dfrac { 1500 }{ { 20 }^{ 2 } } =\dfrac { W }{ { 1 }^{ 2 } } ,\quad W\quad =\quad 3.75\quad kg.$
Hence, weight to be placed on the small piston sufficient to lift a car of mass 1500 kg is 3.75 kg.

To avoid vaporization in the pipe line, the pipe line over the bridge is laid such that it is not more than

  1. 2.4m above hydraulic gradient

  2. 6.4m above hydraulic gradient

  3. 10m above hydraulic gradient

  4. 1.4m above hydraulic gradient


Correct Option: B
Explanation:

To avoid vaporization in the pipe line, the pipe line over the bridge is laid such that it is not more than 6.4m above hydraulic gradient

A hydraulic press has a ram of 15 cm diameter and plunger is 1.5 cm. It is required to lift a weight of 1 tonne. The force required on plunger is

  1. 10kg

  2. 100 kg

  3. 1000 kg

  4. 1 kg


Correct Option: A
Explanation:

Weight on the ram  $F  =  mg=1000\times 10 = 10000$

Using Pascal's law      $\dfrac{F}{A } = constant$              where $A = \pi D^2$
$\therefore$      $\dfrac{10000}{(15)^2 } =\dfrac{F _p}{(1.5)^2}$              $\implies F _p = 100$ N $= 10\ kgf$

Thus, force required on plunger is $10\ kgf$