Skip to main content

Mathematics for Physics

195 Reference Frames

A coordinate system used by an observer to measure positions, times, and velocities of physical events in space and time.

The coordinate-grid definition of a frame. A reference frame is a grid of meter sticks and synchronized clocks. Synchronized clocks are clocks set so that they read the same time at one common instant. This principle is used to assign unique space and time coordinates to an event.

The shared-frame rule. Experimenters at rest relative to one another share one reference frame. At rest is the condition of zero velocity relative to a chosen origin. This principle is used to combine their readings into one consistent record.

The frame dependence of intervals. Time intervals and spatial distances between events depend on which reference frame records them. A time interval is the elapsed time between two events as read by clocks in that frame. This principle is used to account for time dilation and length contraction.

Note: Also called a frame. Also called a frame of reference. See Frame.