Question

Select the correct choice(s)

• A. The gravitational field inside a spherical cavity, within a spherical planet must be non zero and uniform.
• B. When a body is projected horizontally at an appreciable large height above the earth, with a velocity less than for a circular orbit, it will fall to the earth along a parabolic path.
• C. A body of zero total mechanical energy placed in a gravitational field will escape the field
• D. Earth's satellite must be in equatorial plane.

Answer 1

The correct option is C A body of zero total mechanical energy placed in a gravitational field will escape the field

Gravitational field is conservative field, total mechanical energy is conserved.
If a body is in gravitational field with $U+K=0\to K=-U\to \left(1\right)$ i.e. Kinetic energy is non zero.So, it will move away from the field till its kinetic energy is also zero.
If $K=0\to$ U = 0 from (1). But, U = 0 is at $\infty$ and thus the body escapes the field.