Always moving away!

Classical Mechanics Level 4

A projectile is launched at an angle $\theta$ with initial velocity $u$ . Let $\theta = \theta_{max}$ be the largest acute angle for which the projectile is always moving away from its launch point. Determine $\lfloor\theta_{max}\rfloor$ (in degrees).

Details and Assumptions:

$\bullet$ $g \approx 10m/s^2$