Kinematics Question 197
Question: A particle is dropped under gravity from rest from a height $ h(g=9.8m/{{\sec }^{2}}) $ and it travels a distance $ 9h/25 $ in the last second, the height $ h $ it’s [MNR 1987]
Options:
A) 100 m
B) 122.5 m
C) 145 m
D) 167.5 m
Show Answer
Answer:
Correct Answer: B
Solution:
Let h distance is covered in n sec
$ \Rightarrow h=\frac{1}{2}gn^{2} $ -(i) distance covered in $ n^{th} $ sec $ =\frac{1}{2}g(2n-1) $
$ \Rightarrow \frac{9h}{25}=\frac{g}{2}(2n-1) $ -(ii) From (i) and (ii), $ h=122.5\ m $
