What is the "actual" impact velocities of two colliding objects?
Is it relative to the observer, or one of the objects in the collision? The reason I ask is that Marilyn Vos Savant answered a question about this in her column and I think she did it an injustice by saying that: an object moving 50 MPH towards another object moving, say 40 MPH (in the exact opposite direction), that the force of the impact will be.....the same as if each had struck a stationary wall at each of those speeds. I think she is assuming a "perspective" and not taking the relative postion of "observer" or participant into consideration making her answer, inaccurate depending on perspective. (I've seen figures on the "relative" speed of a baseball leaving a bat)
Any enlightenment on this would be appreciated.