Aball is thrown vertically upwards at 19.6 m/s. for its complete trip (up and back down to the starting position), its average speed is:

When the ball reaches its original position, it will have the same speed (but would be traveling in the opposite direction). So the average speed is

regardless of how long the ball was in the air.

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers