# Kinematics of a four bar linkage system

1. Oct 16, 2016

### influx

1. The problem statement, all variables and given/known data

2. Relevant equations
N/A

3. The attempt at a solution

1) The question says that ωAB = ωABk, I understand that bold indicates vectors whilst the plain text indicates a magnitude so ωAB (magnitude) multiplied by k (direction vector) gives you the vector ωAB. However, why do we multiply the magnitude by k (to yield the vector ωAB) as opposed to multiplying by i or j? I'm trying to picture this in my head but struggling to.

2) Am I correct in saying that ωAB = ωBA? That is, does the order of the letters in the subscript of the vector matter? Does this matter for magnitudes (e.g. ωAB = ωBA), vectors^ or both/neither?

2. Oct 20, 2016

### CWatters

This isn't my subject really so I'm not the best person to reply but since you haven't had one...

I believe this is just another way to represent rotation called the Axis–angle representation.

https://en.wikipedia.org/wiki/Axis–angle_representation

and it's scalar multiplication not ordinary or vector multiplication..
https://en.wikipedia.org/wiki/Scalar_multiplication

Last edited: Oct 20, 2016