Correct Answer : Option (D) :   Closed form solution does not exist

Explanation : N-body problems are usually chaotic for initial conditions and require numerical method to compute the result. Analytical results cannot be obtained wince there no closed form solution existing. So far, two body problems and restricted 3-body problem can be solved.

Correct Answer : Option (A) :   One-body problem

Explanation : The simplest case of the N-body problem is a case which has only one body. In the entire space, there lies only one body with mass m. It experiences no force, acceleration and moves with a constant velocity.

Correct Answer : Option (B) :   10^-3 g’s

Explaination : There are certain variations introduced due to the earth’ oblateness effect. This force is of the order 10^-3 g’s. Newton’s law is only applicable for spherical objects.