z-track is used during intramuscular injection to reduce irritation.

Unless you have access to the original recordings with a separate vocal track it is impossible to remove the vocals as they become mixed into a single track with all the other instruments. Depending on the individual track you may be able to reduce them with an equaliser by fading down the mid frequencies but this will also reduce the other instruments too.

Friction. Oonce the train is clear of the track, there is no friction to slow it down.

GPS tracking is one good way to reduce fuel costs for heavy equipment. Many people do not understand that with an embedded gps system, they can track vehilce activity as well as it's location. For instance you can track pto activity, idling time, speeding and of course extra stops.

friction between the box and the track, allowing for smoother movement with less resistance. This reduces the amount of force needed to push or pull the box along the track, ultimately saving energy.