Is a Slowly-Rolling Car Not Dangerous?

Physics can help a person realize that it’s not always good to be hit by a slowly rolling car, even if the ground appears to be flat. This medical report gives details:

Pedestrian accident analysis with a silicone dummy block,” Youngnae Lee, Sungji Park, Seokhyun Yoon, Youngsu Kong, and Jae-Mo Goh, Forensic Science International, vol. 220, no. 1, 2012, pp. e13-e16. The authors at the National Forensic Service (NFS), Seoul, South Korea, report:

A rolling car on a gentle slope seems to be easily halted by human power to prevent damage to the car or a possible accident. However, even if the car rolls down very slowly, it can cause severe injuries to a pedestrian, especially when the pedestrian cannot avoid the rolling car. In an accident case that happened in our province, a pedestrian was injured by a rolling car, which had been parked on a slope the night before. The accident occurred in the parking lot of an apartment complex. The parking lot seemed almost flat with the naked eye. We conducted a rolling test with the accident vehicle at the site. The car was made to roll down the slope by purely gravitational pull and was made to collide with the silicone block leaning against the retaining wall. Silicone has characteristics similar to those of a human body, especially with respect to stiffness. In the experiment, we measured the shock power quantitatively. The results showed that a rolling car could severely damage the chest of a pedestrian, even if it moved very slowly.

Improbable Research