Tag: option b: engineering physics

Questions Related to option b: engineering physics

A jet of water with cross section of $6{ cm }^{ 2 }$ strikes a wall at an angle of ${ 60 }^{ \circ  }$ to the normal and rebounds elastically from the wall without losing energy. If the velocity of the water in the jet is $12 m/s$, the force acting on the wall is

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $0.864N$

  2. $86.4N$

  3. $72N$

  4. $7.2N$

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Correct Option: B
Explanation:
F = $\dfrac{dP}{dt}$
   = $\dfrac{2 dm V\cos 60^o}{dt}$
   = $\dfrac{2 (\rho A dx) V\cos 60^o}{dt}$
   = $2 \rho A {V}^2\cos 60^o$
   = ${10}^3\times 6\times {10}^{-4} \times{12}^2$
   =$86.4N$

The Kinetic energy per cubic metre of a perfect gas at N.T.P. is ( Take atmospheric pressure $ = 1 \times {10^5}N/{m^2})$)

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $1.5 \times {10^5}J/{m^3}$

  2. $2 \times {10^5}J/{m^3}$

  3. $0.75 \times {10^5}J/{m^3}$

  4. $2.5 \times {10^5}J/{m^3}$

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Correct Option: B

Power of a water pump is 2 kW. If $g=m/{ sec }^{ 2 }$, The amount of water it can raise in one minute to a height of 10 m/s 

physics option b: engineering physics buoyancy floatation fluid pressure

  1. 100 Litre

  2. 1200 Litre

  3. 1000 Litre

  4. 2000 Litre

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Correct Option: B

A wide vessel with a small hole in the bottom is filled with water and kerosene. Neglecting the viscosity, find the velocity of the water flow, if the thickness of the water layer is equal to $\mathrm { h } _ { 1 } = 30 \mathrm { cm }$ and that of the kerosene layer to $h _ { 2 } = 20 \mathrm { cm }$.Density of kerosene $= 600 \operatorname { kg } / m ^ { 3 }$

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $5.74 \mathrm { ms } ^ { - 1 }$

  2. $1.91 \mathrm { ms } ^ { - 1 }$

  3. $2.87 \mathrm { ms } ^ { - 1 }$

  4. $3.82 \mathrm { ms } ^ { - 1 }$

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Correct Option: C

A pump motor is used to deliver water at a certain rate from the given pipe. To obtain 'n' times water from the same pipe in the same time, the amount of power of the motor should be increased to:

physics option b: engineering physics buoyancy floatation fluid pressure

  1. np

  2. ${n^3}$

  3. ${n^2}$

  4. 2np

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Correct Option: B

Equal amount of same gas in two similar cylinders $A \text { and } B$,compressed to same final volume from same initial volume one adiabatically and another isothermally, respectively then  

physics option b: engineering physics buoyancy floatation fluid pressure

  1. final pressure in $A$ is more than in $B$

  2. final pressure in $B$ is greater than in $A$

  3. final pressure in both able equal

  4. for the gas, value of $\gamma = \frac { C _ { p } } { C _ { V } }$

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Correct Option: A

Water flows into a large tank with flat bottom at the rate of $  10-4 \mathrm{m}^{3} \mathrm{s}-1  $ . Water is also leaking out
of a hole of area 1 $  \mathrm{cm}^{2}  $ at its bottom. If the height of the water in the tank remains steady, then this height is:

physics option b: engineering physics buoyancy floatation fluid pressure

  1. 4 cm

  2. 2.9 cm

  3. 1.7 cm

  4. 5.1 cm

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Correct Option: C

The height to which a cylindrical vessel be filled with a homogeneous liquid, to make the average force with which the liquid presses the side of the vessel equal to the force exerted by the liquid on the bottom of the vessel is equal to:

physics option b: engineering physics buoyancy floatation fluid pressure

  1. half of the radius of the vessel.

  2. radius of the vessel.

  3. one-fifth of the radius of the vessel.

  4. three-fourth of the radius of the vessel.

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Correct Option: B
Explanation:

If $h$ is the height of liquid in cylinder, $r$ be the radius of the cylinder and $\rho$ be the density of the liquid. then we have
weight of the liquid $=\pi { r }^{ 2 }h\rho g          ....... (I)$
Mean pressure on the wall $=\frac{1}{2} \rho g h $
force on the wall $=\frac{1}{2} \rho g h \times 2 \pi r h=\pi r \rho g h^2          ....... (II)$
On equating $(I)$ and $(II)$ we have
$\pi { r }^{ 2 }h\rho g=\pi r \rho g h^2$
$\Rightarrow r=h$
i.e. the liquid should be filled up-to a height equal to the radius of the cylinder.

A thermally insulated cylinder is divided into two equal halves by a thermally insulated wall. One half contains He at 600$\mathrm { K }$ and the other contains $\mathrm { H } _ { 2 }$ at 800$\mathrm { K }$ , pressure being same in two parts equal to $P _ { 0 }$ . Now, the wall is removed and two gases mix. The resulting pressure is

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $P _ { 0 }$

  2. 2$P _ { 0 }$

  3. $\frac { 28 P _ { 0 } } { 54 }$

  4. $\frac { 28 P _ { 0 } } { 27 }$

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Correct Option: D

Two identical cylinders contain Helium at 2.5atmosphere and Argon at 1 atmosphere respectively. If both gases are transferred in one ofthe cylinders, what is the new pressure? 

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $3.5$ atmosphere

  2. $1.5$ atmosphere

  3. $1.75$ atmosphere

  4. $1$ atmosphere.

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Correct Option: A