Gravitation

MCQs (Part - X)

Question 46: A gravitational field is present in a region. A point mass is shifted from A to B, from different paths shown in the figure. If W1, W2 and W3 represent work done by gravitational force for respective paths, then:

  1. W1 = W2 = W3
  2. W1 > W2 > W3
  3. W1 > W3 > W2
  4. none of these

Answer: (a) W1 = W2 = W3

Explanation: The work done by gravitional force does not deend upon path. So, work done in all paths are same.

Question 47: Two identical spherical masses are kept at some distance as shown. Potential energy when a mass m is taken from surface of one sphere to the other:

  1. increase continuously
  2. decreases continuously
  3. first increases then decreases
  4. first decreases then increases

Answer: (c) first increases then decreases

Explanation: Centre point is unstable equilibrium position where potential energy is maximum.

Question 48: A point mass m0 is placed at distance R/3 from the centre of a spherical shell of mass m and radius R. The gravitational force on the point mass m0 is:

  2. zero
  4. none of these

Answer: (b) zero

Explanation: The gravitational field inside the spherical shell is zero. Hence, gravitational force on the point mass m0 is zero.

Question 49: n-particles each of mass m0 are placed on different corners of a regular polygon of edge length a. The distance between vertex and centre of polygon is r0. The gravitational potential at the centre of the polygon is:

  4. none of these

Answer: (a)

Explanation:


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