The updated side crash test uses a heavier barrier traveling at a higher speed to simulate the striking vehicle. The new barrier weighs 4200 pounds, about the weight of today’s mid-size SUVs, and strikes the test vehicle at 37 mph, compared with a 3300-pound barrier traveling at 31 mph in the original test. Newton understood this in his F=MA equation. That is, Newton’s second law says that force is proportional to what is required for an object of constant mass to change its velocity. This equals the object’s mass multiplied by its acceleration. The increase in weight (Mass) and speed (Acceleration) results in a substantial increase in the energy (Force) involved in such an accident or test.