Question

two balls fall freely from the heights in the ratio 1:4 Find the ratio of times for the ball to reach the ground.

Answer 1

\[s= ut +\frac{ 1 }{ 2 } at ^{2} \]

Use this kinematic relation.
s=displacement
u=initial velocity
a=acceleration=g in this case
t=time

For you question

u=0
hence
\[s= \frac{ 1 }{ 2 } a t ^{2}\]

or

\[\frac{ s1 }{ s2 } = (\frac{ t1 }{ t2 })^{2} \]

s1/s2 is given in the question=1/4

You can find t1/t2 like this = 1/2