Gravitation

MCQs (Part - VII)

Question 31: If the earth stops rotating about its axis, the acceleration due to gravity will remain unchanged at:

  1. equator
  2. latitude 45º
  3. latitude 60º
  4. poles

Answer: (d) poles

Question 32: The gravitational field in a region is 10 N/kg The work done by gravitational force to shift slowly a particle of mass 1 kg point (1 m, 1m) to a point (2m, – 2m) is:

  1. 10 J
  2. – 10 J
  3. – 40 J
  4. + 40 J

Answer: (d) + 40 J

Question 33: In previous problem, the work done by external agent is:

  1. 40 J
  2. - 40 J
  3. zero
  4. + 10 J

Answer: (b) - 40 J

Explanation Since, particle is shifted slowly so, change in kinetic energy is zero.

According to work-energy theorem

W + Wext = 0

Wext = – W = – 40 J

Question 34: The gravitational force in a region is given by

The work done by gravitational force to shift a point mass m from (0, 0, 0) to (x0, y0, z0) is:

  1. ma x0y0z0
  2. ma x0y0
  3. ma x0 y0
  4. zero

Answer: (b) max0y0

Question 35: Let V and E be the gravitational potential and gravitational field at a distance r from the centre of a hollow sphere. Consider the following statements.

(A) The V-r graph is continuous

(B) The E-r graph is discontinuous

  1. Both (A) and (B) are wrong
  2. Both (A) and (B) are correct
  3. (A) is correct but (B) is wrong
  4. (A) is wrong but (B) is correct

Answer: (b) Both (A) and (B) are correct

Explanation The V-r and E-r graphs for a hollow sphere are as follows:

Thus, V-r graph is continuous while E-r graph is discountinuous.


Copyright © excellup 2014