# Geometric Interpretation for Virtual Velocity

1. Nov 18, 2009

### DoubleHelics

Hello,
I am having hard time giving a geometric interpretation for the virtual velocity in classical mechanics, defined as:
$$\delta \dot{x} = \frac{d}{dt} \delta x$$
where $$\delta$$ is the virtual differential operator, and $$\delta \dot{x}$$ denotes the virtual velocity of $$x$$. I think having a geometric interpretation would make it much easier to understand the intuition behind the virtual velocity. I found one explanation in Rosenberg's Analytical Dynamics book, Section 9.5 on page 140, but I am not very satisfied with it since it just illustrates why the time derivative of virtual displacement should exist, which I can already understand.

Any comments, books or other resources on this is greatly appreciated!

I am new here, and I just wanted to say that I love the ability to type latex into the posts!

D.