Two balls are dropped from heights h and 2h respectively from the earth surface. The ratio of time of these balls to reach the earth is:
A
1 : \sqrt{2}
B
\sqrt{2} : 1
C
2 : 1
D
1 : 4
Step-by-Step Solution
Principle: For a body in free fall starting from rest (u=0), the distance fallen (h) in time (t) is given by the kinematic equation:
h=ut+21gt2⇒h=21gt2
Relation: This implies that time is proportional to the square root of the height:
t=g2h⇒t∝h .
Calculation:For the first ball (h1=h): t1∝h For the second ball (h2=2h): t2∝2h
Ratio:t2t1=2hh=21
The ratio is 1:2.
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