Gravitation

MCQs Answer (Part - IV)

Question 16: A body is projected vertically from the earth's surface with velocity equal to half of the escape velocity. Maximum height reached by the body is:

Answer: (b)

Explantion: From conservation of mechanical energy

or,

Question 17: If the radius of the earth reduces by 4%, density remaining the same, then the escape velocity will:

  1. increase by 4%
  2. increase by 2%
  3. decrease by 4%
  4. decrease by 2%

Answer: (c) decrease by 4%

Question 18: The time period of artificial satelite in a circular orbit of radius R is T. The radius of the orbit in which time period is 8T is:

  1. 2 R
  2. 3 R
  3. 4 R
  4. 5 R

Answer: (c) 4 R

Explantion:

and

or

or R' = 4R

Question 19: A satellite is orbiting very colse to planet. Its time period depends only upon:

  1. density of the planet
  2. mass of the plane
  3. radius of the planet
  4. mass of the satellite

Answer: (a) density of the planet

Question 20: A body is projected with escape velocity 11.2 km/s from earth's surface. If the body is projected in a direction 30º angle to the vertical, its esacpe velocity in this case will be:

  1. 11.2 km/s
  2. none of these

Answer: (a) 11.2 km/s

Explantion: Escape velocity does not depend on angle of projection, so it will remain same i.e., 11.2 km/s.


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