The second impact is the impact suffered between a vehicle occupant and the vehicle he or she is riding in during some kind of safety incident. The first impact is the impact between the vehicle and another object. There is also a third impact between the internal organs and the frame of the body.

The term was coined in the 1950s by Sergeant Elmer Paul of the Indiana State Police

Indiana State Police

The Indiana State Police is the statewide law enforcement agency for the state of Indiana. Indiana was the 12th state to offer protection to its citizens with a state police force.-History:...

. Paul convinced Indiana authorities to investigate the mechanics of highway injuries, and worked with safety pioneer Hugh DeHaven.

The effects of the second impact are reduced by the use of seat belt

Seat belt

A seat belt or seatbelt, sometimes called a safety belt, is a safety harness designed to secure the occupant of a vehicle against harmful movement that may result from a collision or a sudden stop...

s, airbag

Airbag

An Airbag is a vehicle safety device. It is an occupant restraint consisting of a flexible envelope designed to inflate rapidly during an automobile collision, to prevent occupants from striking interior objects such as the steering wheel or a window...

s, interior vehicle padding and removing of aggressive structures.