# Basic forces/friction

1. Oct 11, 2004

### nycon

Hello, I'm on my way to having a test on "Forces/Friction" very soon in the future, but the thing is Im stuck :( my teacher wont really help me out. He only states the answer doesn't show how to achieve it at all. So I was wondering if anyone could tell me some basic formulas, and examples that could help me out?

Thanks John

2. Oct 11, 2004

### Pyrrhus

All you need to learn for Linear Dynamics, also learn how to do Free Body diagrams.

Newton's 1st Law

$$\sum_{i=1}^{n} \vec{F}_{i} = 0 \rightarrow \vec{v} = constant$$

Newton's 2nd Law

$$\sum_{i=1}^{n} \vec{F}_{i} = m \vec{a}$$

Newton's 3rd Law

$$\vec{F}_{12} = -\vec{F}_{21}$$

Friction Force Magnitude

$$F_{f} = \mu N$$

3. Oct 11, 2004

### Tanya Back

WOW same here..i am having a test on friction/forces very soon too! and i also got a teacher dat sucks!