This is a solution to the "Speed Estimate from Crush" question. It is meant only to display the math "I" used to resolve it. These methods can be found in numerous publications including NUTI Topic Book #870 "Work, Energy and Speed from Damage in Traffic Accidents", SAE Paper #910119 "Stiffness Parameters for Vehicle Collision Analysis from Crash Test(s) for Crash Data" and in the SLAM Technical Manual.

Information as follows was given in order to permit the resolution of an estimate of the subject vehicle's speed:

• Both the test and the subject vehicle were 1984 Ford Mustangs
• The weight of both vehicles was 3240 lbs.
• The test vehicle and the subject vehicle were both crushed across their respective 68 inch wide fronts
• The test vehicle's average crush depth was 20 inches at a speed of 30 MPH. This is coincidentally a ratio of 1.5 MPH per inch of crush, which is an old rule of thumb equation.
• The subject vehicle's average crush depth was 36 inches. Using the rule of thumb equation mentioned above we end up with 36 x 1.5 = 54 MPH. Using two well known sets of equations/methods let's see how close that rule of thumb actually is.

The first method has been around as long as the CRASH computer program:

The second method calls for the determination of crush coefficients, which will be used in quantifying Kinetic Energy dissipation.

As if two systems weren't good enough I ran these figures through the SLAM computer program and it also predicted a dissipation of 270,617 ft/lbs. of energy, which equates to 50 MPH.

This is a rare case where closing speed, Delta V and EBS all have the same value.