# I Center of Mass Velocity in Multiple Dimmensions

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1. Aug 13, 2017

### tummbacoco

I was doing some practice problems to become more familiar with the Center of Mass Velocity and I came across this one from (Noted in the picture) Engineering at Illinois, that relates the velocity of the center of mass in both the x and y direction, however I don't quit understand the answer.

VCM = (M1V1 + M2V2)/ Mtotal

Since this is the case VCM should equal 2.4, but the question asked for the velocity in the x and y direction

Since only one object is moving in the x-direction shouldn't that be the VCM for the x-direction??
Why would VCM (x-direction) = Momentum in the x-direction? How would one go about calculating VCM for individual dimensions? Thanks!

2. Aug 13, 2017

### BvU

No. As you see in the formula,
There are factors $m_1/m_{\rm total}$ and $m_2/m_{\rm total}$

It isn't. $v_{\rm} \;m_{\rm total}$ is the momentum.

3. Aug 13, 2017

### Ibix

The easiest way to do it is to remember that velocity is a vector, which you seem to have forgotten when you got your 2.4m/s answer.