<P> An inertial frame of reference in classical physics and special relativity is a frame of reference in which a body with zero net force acting upon it is not accelerating ; that is , such a body is at rest or it is moving at a constant speed in a straight line . In analytical terms , it is a frame of reference that describes time and space homogeneously , isotropically , and in a time - independent manner . Conceptually , the physics of a system in an inertial frame have no causes external to the system . An inertial frame of reference may also be called an inertial reference frame , inertial frame , Galilean reference frame , or inertial space . </P>
<P> An inertial frame of reference in classical physics and special relativity is a frame of reference in which a body with zero net force acting upon it is not accelerating ; that is , such a body is at rest or it is moving at a constant speed in a straight line . In analytical terms , it is a frame of reference that describes time and space homogeneously , isotropically , and in a time - independent manner . Conceptually , the physics of a system in an inertial frame have no causes external to the system . An inertial frame of reference may also be called an inertial reference frame , inertial frame , Galilean reference frame , or inertial space . </P>
when can an inertial system be also considered a reference system
when can an inertial system be also considered a reference system
a body with zero net force acting upon it is not accelerating
a body with zero net force acting upon it is not accelerating