The parcel, perturbed vertically from its starting position, experiences a vertical acceleration.

The vertical acceleration was far greater than the horizontal acceleration.

In these special conditions, vertical accelerations up to twice the force of gravity have been measured.

Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection.

Each channel is designed to record one of the plane's vital measurements, like speed, altitude, heading and vertical acceleration.

To achieve low orbit requires much more horizontal than vertical acceleration.

Then, six seconds before the impact, the flight data recorder showed "significant changes in air speed, heading, altitude, and vertical acceleration," he said.

This bends the stereocilia, which is interpreted by the brain as vertical linear acceleration.

Learn how vertical acceleration works in this article.

The vertical acceleration of this helicopter is amazing.