Helmet v Mask

[dddunn3d]

mbryon is correct when he states that acceleration is a change in velocity over a period of time. However, almost everyone here is confusing velocity with speed. Velocity is a vector, that is, it has both magnitude and direction.

Acceleration also is a vector. That's why when one twirls a model airplane around one's head by attaching it to a length of string, the speed may remain constant, but the model is being accelerated towards the center of rotation.

I could go on by throwing in F=ma, and relating how acceleration implies a force acting on a body, etc. etc., but I won't bore you any longer.

[Edited by dddunn3d on Sep 19th, 2005 at 08:20 AM]