A.D. Tupper & Associates Limited

Angular Momentum Analysis

Although, it is not used so frequently in reconstruction analyses as its linear cousin, angular momentum is also conserved during a collision. Therefore, any angular momentum lost by one vehicle is gained by the other. The principles of angular momentum can also be observed in a billiard game. When a spinning billiard ball subsequently strikes another ball, some of the spin will be transferred to the struck ball. The same thing occurs with other bodies.

 Angular momentum is more difficult to apply to reconstruction than linear momentum. There are two basic reasons for this difficulty, namely:

  1. While linear momentum requires the weight of a vehicle, angular momentum requires the rotational inertia. Rotational inertia values are significantly more difficult to obtain than weights.
  2. The angular deceleration must be evaluated. Reasonable values for the rotational deceleration can be very difficult to obtain and usually require extensive computation.

 The easy way to handle the computation is with a computer and angular momentum is evaluated in some reconstruction software.