I am confused how they picked the direction right of block M1 to be -x and the downward direction of block M2 to be +x..?(adsbygoogle = window.adsbygoogle || []).push({});

I didn't know that one could create two different coordinate axis.

Correct me if I am wrong but it seems that if you are working with two diff body's that are not in contact you can create diff axis for both body's.. but if two body's are in contact then you have to use the same axis for both body's?

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# Correct coordinate axis

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