## 2-1: Position, Velocity, and Speed

Position: is the location of the particle with respect to a chosen reference point that we can consider to be the origin of a coordinate system.

Displacement: the displacement  $\Delta x$  of a particle is defined as its change in position in some time interval. As the particale moves from an initial position  $x_{i}$  to a final position  $x_{f}$  its displacement is given by:

 $\Delta x\equiv x_{f}-x_{i}$   (2-1)

Distance: is the length of a path followed by a particle. distance is always represented as a positive number, whereas displacement can be either positive or negatve.

Average velocity$\nu _{x,avg}$  of a particle is defined as the particle’s displacement  $\Delta x$  divided by the time interval  $\Delta t$  during which that displacement occus:

 $\nu _{x,avg}\equiv \frac{\Delta x}{\Delta t}$   (2-2)

Average speed:  $\nu _{avg}$  of a partical, a scalar quantity, is defined as the total distance  $d$  traveled divided by the total time interval required to travel that distance:

 $\nu _{avg}\equiv \frac{d}{\Delta t}$  (2-3)

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Physic:S&E,8E