Assertion:  An astronaut experience weightlessness in a

Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Height of geostationary satellite is

  • 16000 km

  • 22000 km

  • 28000 km

  • 36000 km


2.

If a solid sphere of mass 1 kg and radius 0.1 m rolls without slipping at a uniform velocity of I m/s along a straight line on a horizontal floor, the kinetic energy is

  • 75 J

  • 25 J

  • 710 J

  • 1 J


3.

In the diagram shown below all three rods are of equal length Land equal mass M. The system is rotated such that rod B is the axis. What is the moment of inertia of the system?

 

  • ML26

  • 43ML2

  • ML23

  • 23 ML2


4.

The direction of the angular velocity vector is along

  • the tangent to the circular path

  • the inward radius

  • the outward radius

  • the axis of rotation


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5.

A man of mass 60 kg records his wt on a weighing machine placed inside a lift. The ratio of wts. of  man recorded when lift is ascending up with a uniform speed of 2 m/s to when it is descending down with a uniform speed of 4 m/s will be

  • 0.5

  • 1

  • 2

  • none of these


6.

The force of gravitation is

  • repulsive

  • conservative

  • electrostatic

  • non-conservative


7.

Which of the following velocity-time graphs shows a realistic situation for a body in motion?


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8.

Assertion:  An astronaut experience weightlessness in a space satellite. 

Reason:  When a body falls freely it does not experience gravity.

  • If both assertion and reason are true and reason s 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


B.

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

Both the statements of assertion and the reason are correct. They are independent statements. The statement given in the reason is not the reason for the weightlessness of the astronaut. The centripetal and centrifugal forces cancel out. In the case of free fall, the pseudo acceleration, ' g ' acts upwards. The -body does not feel it. But all the same it will fall down to the earth. His mind which feels, is riding the lift of his body. The body is falling down with acceleration g. In the first case, the force of acceleration due to gravity is cancelled by the centrifugal force acting outwards. Both the statements are correct but the reason given is not the reason for the assertion.


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9.

Shear modulus is zero for

  • solids

  • liquids

  • gases

  • liquids and gases


10.

If the temperature of a black body increases from 7°C to 287°C then the rate of energy radiation increases by

  • 28774

  • 16

  • 4

  • 2


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