00:01
Okay, let's denote the baseball by subscript a and the brick by subscript b.
00:05
So part a wants the velocity of the baseball after the collision.
00:12
So we use momentum conservation obviously.
00:15
You have initial momentum of the baseball, m -a -v -a.
00:21
That is equal to final momentum of the baseball, m -a -v -a -p -a -p -a -p -b -a -p -b -a -p -b -a -p being final speed, and add to that momentum of the brick mbvb prime.
00:35
So va prime, very simply, is just m -a -v -a -m -b -b -b -p -b -p prime over m -a.
00:45
And so just plugging in values now, ma is 0 .144 kilograms, the baseball.
00:51
The velocity of the baseball before collision is 28 meters per second, minus bricks mass is 5 .25 kilograms.
01:02
Velocity is 1 .1 meters per second.
01:05
Divide that by 0 .144 kilograms.
01:11
Therefore, va prime is found to be negative 12 .1 meters per second.
01:17
So it's 12 .1 meters per second in the opposite direction from its initial direction...