Introduction
Many mechanics problems involve two or more objects being connected together. An example could be two masses connected by a pully, or one block stuck to another block, possible through friction. We call these coupled systems. These systems are often connected by third law force pairs, or just force pairs. And when any two objects are coupled together they must share something in common, such as the magnitude of a tension force or the magnitude of their kinematic variables.
Pulley Assumptions
Key Terms
Text/Video
Physics Classroom: Good introduction with examples
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.
If you'd like to find out more about constraints this web page has some great examples. Specificily look at example 2 and 3;
Finally check out the Important Features and Problem Examples for coupled systems.
Simulations
PHeT Springs: A fun little applet that looks at springs. Don't worry about any of this normal mode buissnes, just explore how changing one spring might effect another.
Atwoods Machine: Another Wiley interactive simulation directly applying concepts from Newton's 2nd Law;
Additional Studying/Review
- Also, here is a great video of a problem solution for coupled systems. Just be aware they use a different symbol for some of the force push and normal force.
- Another great video. This one covers two objects that are accelerating in different directions. (Doesn't clearly deal with the vector nature, which is a feature of almost all online videos)
- A video explaination of Newton's third law is also nice.
- Looking into one of the classic force pair problems, the horse and the cart. How does it move?
- And now for something totally different. This is about horses(and not about physics).
- And can't leave out Bill Nye clearing up one of the hardest questions with Newton's Third Law
- Also here is a great video looking at constraints.