Kinematics Question 215

Question: A stone is shot straight upward with a speed of 20 m/sec from a tower 200 m high. The speed with which it strikes the ground it’s approximately [AMU (Engg.) 1999]

Options:

A) 60 m/sec

B) 65 m/sec

C) 70 m/sec

D) 75 m/sec

Show Answer

Answer:

Correct Answer: B

Solution:

Speed of stone in a vertically upward direction is 20m/s. So for vertical downward motion we will consider $ u=-20\ m/s $

$ v^{2}=u^{2}+2gh={{(-20)}^{2}}+2\times 9.8\times 200=4320\ m/s $ $ v\tilde{-}65m/s $ .



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