Question

If the law of gravitation instead of being inverse square law becomes an inverse cube law

• A. planets will not have elliptic orbits
• B. circular orbits of planets is not possible
• C. projectile motion of a stone thrown by hand on the surface of the earth will be approximately parabolic
• D. there will be no gravitational force inside a spherical shell of uniform density

Answer 1

Answer: (A), (C)

The correct options are
A planets will not have elliptic orbits
C projectile motion of a stone thrown by hand on the surface of the earth will be approximately parabolic

If the law of gravitation becomes an inverce square law, then the planets will have path of form:

as $f\left(r\right)=\frac{K}{r^3}\Rightarrow r={ae}^{\pm 3\theta }$

Where a, K $\Rightarrow$ constants And thus the projectile motion of the stone thrown by hand on earth will be approximately parabolic.