Impact Analysis

Just as in the last lesson, we can usually use the Principle of Impulse and Momentum "across" an impact, and other forms of Newton's Second Law may prove useful before and after the impact.

For oblique central impacts, the bodies exert an impulsive force on each other only along the line of impact. Therefore, using the impulse and momentum equation in this direction introduces this unknown force, which is is generally of little interest to us. However, applying the impulse and momentum equation normal to the line of impact (where there is no impulsive force between the bodies) will show us that the components of velocity in this direction are conserved.

Applying the definition for the coefficient of restitution along the line of impact will generally allow us to relate the components of velocity in this direction.