# A ball is launched vertically upwards from ground level with an initial velocity of 30 m/s. About how much time elapses before it reaches the ground? About what maximum altitude does it reach above ground? Please explain I'm so confused.

##### 1 Answer

I found

#### Explanation:

The ball starts with initial velocity

You can say that the final velocity depends upon the initial velocity AND the contribution of the acceleration that operates for a certain time

in our case:

So you have that the time to reach the maximum height will then be:

This is the time to go up; you double it to consider also the second leg of the trip when the ball comes back to the ground: so:

The maximum height can be found considering:

with our data:

again the acceleration of gravity is directed downwards and we use the time to go up.

So: