00:01
A man with the mass of 91 kilograms.
00:05
I'm going to call this object 1 is lying on a horizontal frictionless surface.
00:10
And so if you're just lying there, your initial velocity is going to be zero.
00:15
And then there is a stone which has a mass of 68 grams.
00:19
You're going to divide that by a thousand to get kilograms, so it's 0 .0 .68 kilograms, which is also originally just laying on the frictionless surface.
00:29
But then the man pushes this stone, giving it a speed of four meters per second.
00:38
And we want to know what is the final speed of the man after this happens.
00:42
So this will be final.
00:46
And so if we look at this, this is going to be a conservation of momentum or the momentum of one person initially or one object initially, plus the momentum of the second object initially, would be equal to both their momentums, finally, after they have interacted.
01:07
And so that is the conservation of momentum.
01:09
Initially, they are both at rest, and so if you're not moving, you do not have momentum.
01:14
So everything on the left side is simply zero...