00:01
All right, so let's say we have a ball dropped from a height of 25 meters at the same end, sorry, not at the same instant, but another ball is thrown upwards at a speed of 19 .6 meters a second.
00:13
We want to know when this ball reaches its maximum height, what is the velocity of the center of mass? so the velocity of the ball thrown at its maximum height is zero.
00:23
So all we have to do is figure out what's the velocity of the dropped ball at that point.
00:28
So let's call the velocity, the initial velocity, u.
00:32
Then the velocity of the dropped ball as it hits the ground is going to be acceleration due to gravity times the time that it's in the air.
00:43
And the time it's in the air is the time it takes the other ball to reach maximum height, which is just going to be u over g.
00:49
And so this is simply u.
00:52
So it'll be 19 .6 meters a second at the point when this one's at maximum height...