At first look we are not able recognize situation
M is moving or m is moving ????

motion is relative ????


big mass M plastycyline
small mass m plastyciline




[img]https://2.bp.blogspot.com/-QvRGmH4z8MU/V...cB/s1600/22.bmp[/img]


Please wait wait ..... after collision we are SURE ! SURE what is going on ....


Big mass M is moving or small m is moving ( after collision exist only one special direction NEW BODY (m+M ) will move there