Q: A small body of super dense material whose mass is twice the mass of the earth but whose size is very small compared to the size of the earth, starts from rest at a height H << R above the earth surface and reaches the earth surface in time t , then t is equal to

(a) $\sqrt{\frac{H}{g}}$

(b) $\sqrt{\frac{2H}{g}}$

(c) $\sqrt{\frac{2H}{3g}}$

(d) $\sqrt{\frac{4H}{3g}}$

Ans: (c)