# How to call ?

Alphanimal
Hi there!
I'm not english, and i learned Physics in German, so i don't know how certain things are called.
I am programming a Rigid Body Dynamics Engine for Macromedia Flash, and i'm often not sure how to name my variables.

Well, how are the following things called in english?
1. The constant factor a spring has, which describes the force it applys (force = (relaxedLength-currentLength)*someFactor)
2. When a spring is compressed/extended, it can have some kind of damping or cushion. (It is calculated by the speed at which the spring is compressed) How would you call this factor (dampForce = compressionSpeed*strangeFactor)
3. Another factor, that decreases speed continously. (every time unit the speed is multiplied my a value between 0 and 1, it has some kind of air-friction effect, causing speed to move against 0)
4. in dynamics programming, first every force is accumulated, and then these forces are integrated (the moment of kinematics) how would you call the step of accumulating Forces, and the Step of making these forces change velocities?
5. The relaxed length of a spring ("relaxed" or "unstressed", ...)

Of what expressions can you think?
Thanks very much!

Gold Member
Alphanimal said:
1. The constant factor a spring has, which describes the force it applys (force = (relaxedLength-currentLength)*someFactor)

This is called the spring constant, spring rate, or occasionally stiffness (not to be confused with the material stiffness). Usually the letter 'k'.

2. When a spring is compressed/extended, it can have some kind of damping or cushion. (It is calculated by the speed at which the spring is compressed) How would you call this factor (dampForce = compressionSpeed*strangeFactor)

The damping constant. Usually the letter c.

I'll probably make a hashed attempt at 3 and 4, so I'll leave those out!

5. The relaxed length of a spring ("relaxed" or "unstressed", ...)

Either of those will do. I tend to use original length, but you could use unloaded or relaxed. Be careful to distinguish between pre-load and post-load lengths, if the spring is permanently deformed by your load.

Alphanimal
Wow thanks very much :) fast answer!
4.: I named them force() and step() for now...
maybe you want to take a look where i am learning dynamics for the engine: http://www.d6.com/users/checker/dynamics.htm
i do not really understand everything (difficult english) but the 2 steps are described there