Vertically Projected Body

(v)Velocity of the body on reaching the point projection (\( V_{striking} \))

Let a body be projected vertically upwards with initial velocity u.
The body reaches the point of projection once again after the time of flight (t_f)
We know that, V = u + at
Here,a=-g, t= t_f=\( \frac{{2u}} {g} \) , V=\( V_{striking} \)  
   \( V_{striking} = u - g\left( {\frac{{2u}} {g}} \right) = - u \) 
  \( V_{striking} = - u \)