Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Assertion: Frictional forces are conservative forces. 

Reason:  Potential energy can be associated with frictional forces.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


12.

Assertion: : For a system of particles under central force field, the total angular momentum is conserved.

Reason:  The torque acting on such a system is zero.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


13.

Which of the following is an amorphous solid?

  • glass

  • diamond

  • salt

  • sugar


14.

For a constant hydraulic stress on an object, the fractional change in the object's volume ( ΔV/V ) and its bulk modulus (B) are related as

  • VV  B

  • VV  1B 

  • VV  B2

  • VV B-2


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15.

Which of the following functions represents a simple harmonic oscillation?

  • sinωt - cosωt

  • sin2ωt

  • sinωt + sin2ωt

  • sinωt - sin2ωt


16.

A candle of diameter d is floating on a liquid in a cylindrical container of diameter D ( D >> d ) as shown in figure. If it is burning at the rate of 2 cm/hour then the top of the candle will

    

  • remain at the same height

  • fall at the rate of 1 cm/hour

  • fall at the rate of 2 cm/hour

  • go up at the rate of 1 cm/hour


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17.

A given shaped glass tube having uniform cross section is filled with water and is mounted on a rotatable shaft as shown in figure. If the tube is rotated with a constant angular velocity  ω when

  • water levels in both sections A and B go up

  • water level in section A goes up and that in B comes down

  • water level in section A comes down and that in B it goes up

  • water levels remain same in both sections


A.

water levels in both sections A and B go up

Due to rotation about the OO', a force is acting on the liquid column AB outwards, pushing up the liquid column AB outwards, pushing up the liquid column on the right. This centrifugal force acting on the small element  'dx'  of  area cross-section 'dx', distant x from the axis is

      dm ω2x =  A dx ρω2x

 

The total force due to the column of length L ( = AB ) is

     0L Aρω2 · x dx = A ρω2 L22

Pressure at B = atmospheric pressure + h1ρg + Aρω2A L22

Pressure at B due to liquid colomn on the right hand side 

                     = atmospheric pressure + h2ρg

Net pressure due to the left-hand side = pressure at B due to liquid column

atm. pressure + h1ρg + ρω2 L22 = atm. pressure + h2ρg

∴     h2 - h1 = H0ω2L22g

Here one has

  H2 =  ω2 L2 22g

  H1ω2L1 22g

As  ω is the same, and L2 > L1, H2 > H1

But both will go up.        


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18.

A magnet is made to oscillate with a particular frequency, passing through a coil as shown in figure. The time variation of the magnitude of e.m.f. generated across the coil during one cycle is


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19.

Assertion:  Specific gravity of a fluid is a dimensionless quantity

Reason: : It is the ratio of density of fluid to the density of water.

  • If both assertion and reason are true and reason is the correct explanation of assertion 

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


20.

Assertion: Reversible systems are difficult to find in real world. 

Reason : Most processes are dissipative in nature.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


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