Changes

where ''x'' is the position and ''v'' is the velocity. The velocity is a [[vector]], and its length or absolute value is called the ''speed''. The velocity has dimensions of length / time, and may thus be expressed in meter per second (in scientific usage). In daily life, miles per hour and kilometers per hour are more common units.

where ''x'' is the position and ''v'' is the velocity. The velocity is a [[vector]], and its length or absolute value is called the ''speed''. The velocity has dimensions of length / time, and may thus be expressed in meter per second (in scientific usage). In daily life, miles per hour and kilometers per hour are more common units.

If an object's [[acceleration]] and velocity have the same sign, the object is gaining [[speed]].  If acceleration and velocity have different signs, the object is losing speed.

For an object moving along a straight trajectory, if [[acceleration]] and velocity have the same sign, the object is gaining [[speed]].  If acceleration and velocity have different signs, the object is losing speed.

If velocity is [[zero]], [[acceleration]] is not necessarily zero. If acceleration is zero, velocity is not necessarily zero.

If velocity is [[zero]], [[acceleration]] is not necessarily zero. If acceleration is zero, velocity is constant, but not necessarily zero.

[[Category:Physics]]

[[Category:Physics]]

[[Category:Mechanics]]

[[Category:Mechanics]]