Why does a whip snap when you swing it?

Question

I was just wondering. I've been writing random stories, and this came up.

Answer 1

The very tip of the whip literally creates  a small sonic boom; it accellerates that much.

Answer 2

Answer with another question:

What was the first man-made object to pass the speed of sound? Answer: a bull-whip.

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Answer 3

The tip of the whip passes the speed of sound creating a sonic boom.