Question

Two objects with different masses are thrown from same height .Will they reach the surface at the same time.Justify.

Answer 1

Yes because gravitational constant is same for all objects no matter what the mass of the object.

Answer 2

assuming that they are freely falling body,
that is initial velocity
u1=u2=0

acceleration on both body by earth is g
from s = ut +(at^2)/2
we can say s1 =s2=(at^2)/2
travelling same distance in time so they reach ground at same time