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.
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.