(a) Horizontal component of velocity $\upsilon_{x} = 500\ m/s$ and vertical components of velocity while striking the ground
$\upsilon_{y} = 0 + 10 \times 10 = 100\ m/s$
$\therefore$ Angle with which it strikes the ground
$\theta = \tan^{- 1}\left( \frac{\upsilon_{y}}{\upsilon_{x}} \right) = \tan^{- 1}\left( \frac{100}{500} \right) = \tan^{- 1}\left( \frac{1}{5} \right)$