According to wikipedia $${\text{Coefficient of restitution }}(e)={\frac {\left|{\text{Relative velocity after collision}}\right|}{\left|{\text{Relative velocity before collision}}\right|}}$$ where relative velocities should be taken along line of impact
But does this relative velocity include effect of other forces than of collision, i.e. using it during calculation in a collision problem, should it signify whole situation or just the collision part.
suppose during a collision, i have restricted a body to move only in horizontal plane (by providing impulsive forces). so for coefficient of restitution of collision what should be considered, final original velocity of body, or the velocity it would have had if there were no restrictions?
