00:01
In this problem, we're going to talk about the gravitational acceleration.
00:04
So remember that the gravitational acceleration g is 9 .8 meters per second square.
00:13
Also remember that the speed, v is equal to the initial speed minus g times t.
00:24
And here i'm considering that the y -axis is pointing upwards, meaning that the positive velocity is pointing up.
00:33
The negative velocity is pointing downwards, and g, the acceleration, the gravity's exploration, is pointing downwards.
00:45
Furthermore, y, the position is equal to the initial position y0, plus the initial velocity v0t, minus g, t squared over 2.
01:00
Okay? so we have a ball that's kicked up in the air and returns to the ground after a time of 5 .2 seconds.
01:13
And in question a, we have to find what is the greatest height, the maximum height, that the ball reaches.
01:25
Notice that the maximum height must happen exactly at half the time it takes for the ball to return to the ground.
01:32
I'm going to call it t prime.
01:35
This is equal to half of 5 .2, so this is equal to 2 .6 seconds...