Difference between Path length and Displacement
Path length
- The actual distance travelled by object in entire motion is known as path length
- It is a scalar quantity
- The dimensions of path length are same as that of length, i.e. [M0L1T0].
- The SI unit of path is meter.
- Path length cannot be zero or negative.
- Suppose a boy is standing along X-axis at the point x1=2 m and x2=9 m, then the distance travelled by the boy will be x2– x1= 9 – 2 = 7 m.
Displacement
- The shortest distance between initial and final position of object is known as displacement.
- It is a vector quantity.
- The dimensions of displacement are same as that of length, i.e. [M0L1T0].
- The SI unit of displacement is meter.
- Displacement can be zero or negative.
- Suppose a boy is starts his motion along X-axis from point A(x1=1) m then to point (B x2=6 m), then to point C(x2=10) and finally reached to the point B, then the displacement of the boy will be,
∆x = x2 – x1
∆x = 6 – 1
∆x = 5 m
7) If suppose the boy comes backs to point A again in reverse manner, then the displacement of boy will be,
∆x = x1 – x1
∆x = 0
Since here the initial position and final position of object of is same, hence the displacement is zero.
8) In above case, though the displacement of boy is zero, but the distance travelled by him will be given as,
∆x = 2(distacne between point A and C)
∆x = 2(9)
∆x = 18 m
9.) This discussion concludes that the magnitude of displacement can be zero, but that of path length or distance can not be zero.