question_answer

A boy standing at the top of a tower of 20 m height drops a stone. Assuming \[g=10\text{ }m{{s}^{-2}}\], the  velocity with which it hits the ground is

A) \[10.0\,m/s\]      

B) \[20.0\,m/s\]

C) \[40.0\,m/s\]      

D) \[5.0\,m/s\]