Primary resources

The OpenStax text book introduces the fundamentals of coupled systems

Physics Classroom: Good introduction with examples, and it has a great lay out that will lead you through different coupled systems and works example problems to show you how objects might interact.

https://www.youtube.com/watch?v=SBRyluYjqxY

https://www.youtube.com/watch?v=KVMF5-kW994

Secondary Resources

If you'd like to find out more about constraints this web page has some great examples. Specifically look at example 2 and 3;

Other Resources

Try to derive the sytem of equations that describes the forces on the two weights attached to an Atwood Machine then read this page about the Atwood Machine and try different calculations at the bottom of the page;

Acceleration with friction: Table with pulley and two objects, 

https://www.youtube.com/embed/SBRyluYjqxY

Horse and cart problem: 

https://www.youtube.com/embed/KVMF5-kW994

If you'd like to find out more about constraints this web page has some great examples.