Simplifying assumptions:
(1) Impacts are all head on.
(2) Stoppage is immediate.
kinetic energy in foot poundals =
= 0.5 * (mass of the vehicle) * ((speed of the vehicle in feet per second)^2)
1 foot poundal = (feet squared) • (pounds) / (seconds squared)
1 mile per hour = 1.467 feet per second
1 foot poundal = 0.04214 Joules
1 short ton (USA) = 2,000 pounds avoirdupois
1 slug = 32.17 pounds avoirdupois
1 poundal = (1 pound) / (1 gravity) = 1 / 32.17 = 0.03108 pounds avoirdupois
If two vehicles run into each other head on, the total kinetic energy is:
total kinetic energy =
= (kinetic energy of first vehicle) + (kinetic energy of second vehicle)
The equivalent speed of impact for the first vehicle to give the same amount of kinetic energy as the head-on collision:
equivalent speed of first vehicle in feet per second =
= SQRT(((actual velocity of first vehicle)^2) + ((mass of second vehicle) / (mass of first vehicle) * ((actual velocity of second vehicle)^2)))
