Two point objects of masses 1.5 g and 2.5 g respectively area at

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 Multiple Choice QuestionsMultiple Choice Questions

211.

A pellet of mass 1 g is moving with an angular velocity of 1 rad/s along a circle of radius 1 m the centrifugal force is

  • 0.1 dyne

  • 1 dyne

  • 10 dyne

  • 100 dyne


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212.

Two point objects of masses 1.5 g and 2.5 g respectively area at a distance of 16 cm apart, the centre of gravity is at a distance x from the object of mass 1.5 g where x is

  • 10 cm

  • 6 cm

  • 13 cm

  • 3 cm


A.

10 cm

Taking the moment of forces about centre of gravity G is

    (1.5) gx = 2.5 g (16 − x)

⇒ 3x = 80 − 5x or 8x = 80 or x = 10 cm


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213.

The weight of a body on surface of earth is 12.6 N. When it is raised to a height half the radius of earth its weight will be

  • 2.8 N

  • 5.6 N

  • 12.5 N

  • 25.2 N


 Multiple Choice QuestionsShort Answer Type

214.

Calculate the distance below and above the surface of the earth, at which the value of acceleration due to gravity becomes 1/4th that at earth's surface ?


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 Multiple Choice QuestionsMultiple Choice Questions

215.

The height vertically above the earth's surface at which the acceleration due to gravity becomes 1% of its value at the surface is (R is the radius of the earth)

  • 8 R

  • 9 R

  • 10 R

  • 20 R


216.

The change in the gravitational potential energy when a body of mass m is raised to a height nR above the surface of the Earth is (Here R is the radius of the earth)

  • nn + 1 mgR

  • nn - 1 mgR

  • nmgR

  • mgRn


217.

If g is the acceleration due to gravity on the surface of the earth, the gain in potential energy of an object of mass m raised from the earth's surface to a height equal to the radius R of the earth is

  • mgR4

  • mgR2

  • mgR

  • 2mgR


218.

Average distance of the Earth from the Sun is L1. If one year of the Earth = D days, one year of another planet whose average distance from the Sun is L2 will be

  • D L2L12 days

  • D L2L13/2 days

  • D L2L12/3 days

  • D L2L1 days


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219.

A stone falls freely under gravity. It covers distances h1, h2, and h3, in the first 5 seconds, the next 5 seconds and the next 5 seconds respectively. The relation between h1, h2, and h3 is

  • h1 = 2h2 = 3h3

  • h1 = h23 = h25

  • h2 = 3h1 and h3 = 3h2

  • h1 = h2 = h3


220.

A body of mass m taken from the earth's surface to the height equal to twice the radius (R) of the earth. The change in potential energy of body will be

  • mg2R

  • 23 mgR

  • 3 mgR

  • 13 mgR


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