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

The average velocity of an object is given by:
Average velocity = total displacement / total time

First, we calculate the time taken to reach the maximum height of the ball. This occurs when the final velocity is 0.
Vf = Vi + at
0 = 19.6 - 9.81 * t
t = 2 seconds

The total trip will be of 4 seconds (2 seconds up, 2 seconds down)

The total displacement is given by:
s = ut + 1/2 * at²
s = 19.6 * 2 - 0.5 * 9.81 * 2²
s = 19.6 meters

This is the distance maximum height, so the total height is
19.6 * 2 = 39.2 meters

Average velocity = 39.2 / 4
Average velocity = 9.8 m/s

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.