00:01
In this problem, we have two people on rollerblades who start a distance one meter apart and then push off.
00:11
So we're asked first, what is their initial center of mass, and then what is their center of mass when at a later time, say when they are four meters apart? so what we're looking at here is, well, first to find the center of mass, just the basic definition of center of mass position times mass individually.
00:40
Right? so our x center mass equals the xi, m i, over the m total.
00:57
Right and then we're also looking at conservation of momentum to determine that our center of mass is going to remain the same so what this means is that our center of mass starts out closer to our heavier person our 75 kilogram person and it will remain relatively it will remain the same and it will remain closer to our 75 kilogram person.
01:31
So first, what is their initial center of mass? and that will just simply look at our 50 kilogram person as at zero.
01:47
So our x center of mass will just be the 75 kilogram person at a distance of one over.
01:59
Over the total mass of 50 plus 75...