**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**

**Solution:**

The correct answers are

(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