What is "decelerations"

Usage examples of "decelerations".

Possibly the restraints he had seen on his bed’s frame would be gentler, but the decelerations when the boat struck the ice mass were so abrupt that he doubted being horizontal would help much.

Possibly the restraints he had seen on his bed's frame would be gentler, but the decelerations when the boat struck the ice mass were so abrupt that he doubted being horizontal would help much.

He moved to where the holes were, moving the oncoming traffic over, and was able to avoid accelerations, decelerations, and the use of the brakes.