sinks in his teeth.

[Ju]

Sink your teeth into this and see if you can't manage this project. He'll find it easier when he sinks in his teeth.

__________________________________________________ _________
What does it mean of:

1. Sink your teeth into
2. sinks in his teeth.

Ju

[Rolex_Cellini]

to start to do something with a lot of energy and enthusiasm

sink teeth into - Idioms - by the Free Dictionary, Thesaurus and Encyclopedia.

[emsr2d2]

Sink your teeth into this and see if you can't manage this project. He'll find it easier when he sinks in his teeth.

__________________________________________________ _________
What does it mean of:

1. Sink your teeth into
2. sinks in his teeth.

Ju

The first use sounds fine. The second doesn't.

"Sink your teeth into this" - Correct
"...find it easier when he sinks in his teeth" - Not a construction I've ever heard.

"You'll find it easier when you really sink your teeth into it".

The word order, in my opinion, is important. If someone "sinks in his teeth", that makes me think of a person drowning, surrounded by their own teeth!!!