What is an example of external control that maintains an ethnic groups' identity?

An internal control that maintain an ethinic groups identity could be passing down the traditions of that cultures to the kids like the music of that culture or could be having to participate in certain religious practices.

Explanation:

For example, lets say your hispanic and you have kids the internal conrol would be to pass down the hispanic music to your kid.

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ek = (m·v2) / 2

v - velocity of system after the collision

m = m1 + m2

ek = (m1 + m2) ·v2/2

ek = (200 + 250) ·2,32/2 = 450·5,29/2 = 1190,25 j