Kinematics Question 209
Question: A body dropped from a height $ h $ with an initial speed zero, strikes the ground with a velocity $ 3km/h $ . Another body of same mass is dropped from the same height $ h $ with an initial speed $ -{u}’=4km/h $ . Find the final velocity of second body with which it strikes the ground [CBSE PMT 1996]
Options:
A) 3 km/h
B) 4 km/h
C) 5 km/h
D) 12 km/h
Show Answer
Answer:
Correct Answer: C
Solution:
For first case $ v^{2}-0^{2}=2gh $
therefore $ {{(3)}^{2}}=2gh $ For second case $ v^{2}={{(-u)}^{2}}+2gh $
$ =4^{2}+3^{2} $
$ \therefore $ $ v= $ 5km/h
