There is a displacement. Just because the ball is thrown up,
and not crossways, doesn't mean its location is not moving. Remember, positive
displacement is together a displacement in the direction east, right, and up.
The velocity is the distance over time. To compute that, you must look how high
the ball moved before falling back down. Acceleration is expected to be
constant at 9.80m/s^2. That is the force of gravity. But remember that you are disregarding
air friction when you are computing the acceleration.
Running for 300 m at 3 m/s takes 100 seconds and running at 300 m at 6 m/s takes 50 seconds. 100 s + 50 s = 150 s (total time). Total distance is 600 m, so 600 m/ 150 s = 4 m/s.
