A projectile is fired from the origin (at y = 0 m) as shown in the diagram
above. The initial velocity components are Vx = 140 m/s and Vy = 84 m/s.
The projectile reaches maximum height at point P, then it falls and strikes
the ground at point Q, which is 20 m below the launch point. Assuming air
resistance is negligible, what is the horizontal component of the velocity
(Vx) of the projectile at point P?