# A ball is thrown upward from a bridge with an initial velocity of 4.9 m/s. It strikes water after 2s. If $g=9.8 m/s^2$ What is the height of the bridge ?

$(a)\;19.6m \quad (b)\;9.8m \quad (c)\;25m \quad (d)\;50m$

Taking point of projection as orgin and downward direction as positive
and using $s=ut+\large\frac{1}{2}$$at^2 h=-4.9 \times 2 +\large\frac{1}{2}$$ \times 9.8 \times 2^2$
$\quad=9.8m$
Hence b is the correct answer.
answered Jun 20, 2013 by
edited May 23, 2014