If we consider the vertical component it is not a constant always because the acceleration due to gravity(g) act on the ball in the vertical direction. 'g' is positive in downward. So upward it is negative.
The ball is at 80 deg angle to the vertical. So the vertical component of velocity is 43cos80.
`uarr v = u+at`
`v = 43cos80-g*t`
'v' represent the vertical component. It changes with time.