Question

A projectile is launched at an angle above the ground. (upwards). The vertical

component of the projectile's velocity is initially 30 m/s. What is the vertical velocity
after 2.0 seconds of flight?

Answer 1

If you take gravity to be 10m/s^2 (approximately) then after 2 seconds of flight it will decrease to 10m/s

If you take g=9.8 then it will decrease by 2 x 9.8 instead.