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**Distance and Displacement**

**Displacement is the difference between the final position,
x**_{f}, and the initial position, x_{i}.

**A displacement to the right will be a positive displacement.
That is,**

**x
> 0 since**
**x**_{i} < x_{f} .

**For example, starting with x**_{i }= 60 m and ending at
x_{f} = 150 m, the displacement is

**x
= x**_{f} - x_{i} = 150 m - 60 m = 90 m

**A displacement to the left will be a negative displacement.
That is,**

**x
< 0 since**
**x**_{i} > x_{f} .

**For example, starting with x**_{i} = 150 m and ending at
x_{f} = 60 m, the displacement is

**x
= x**_{f} - x_{i} = 60 m - 150 m = - 90 m

**Positions to the right of the origin are
positive.**

**Positions to the left of the origin are negative.**

**Distance is the absolute value of the displacement. Distance is
always positive and tells how far something is from something else
but does not tell us whether it is to the right or to the
left.**

**Units are important in Physics (and in all of Science). In the
lab, we will usually measure distance or displacement in units of
meters (m). Distance or displacement could also be measured in
centimeters (cm) or kilometers (km) or even miles (mi).**

(c) 2005, Doug Davis; all rights reserved