Kinematics Question 211
Question: With what velocity a ball be projected vertically so that the distance covered by it in 5th second is twice the distance it covers in it’s 6th second $ (g=10m/s^{2}) $ [CPMT 1997; MH CET 2000]
Options:
A) 58.8 m/s
B) 49 m/s
C) 65 m/s
D) 19.6 m/s
Show Answer
Answer:
Correct Answer: C
Solution:
$ {h _{n^{th}}}=u-\frac{g}{2}(2n-1) $
$ {h _{5^{th}}}=u-\frac{10}{2}(2\times 5-1)=u-45 $
$ {h _{6^{th}}}=u-\frac{10}{2}(2\times 6-1)=u-55 $ Given $ {h _{5^{th}}}=2\times {h _{6^{th}}} $ .By solving we get $ u=65\ m/s $
