Position and Displacement
Average Velocity and average Speed

Unit 5: Motion and Forces

Position and Displacement

p_&_STo locate an object means to find its position relative to some reference point, often the origin (or zero point) of an axis such as the x axis in the figure. The positive direction of the axis is in the direction of increasing numbers (coordinates), which is to the right in the figure. The opposite is the negative direction.

A plus sign for a coordinate need not be shown, but a minus sign must always be shown. Changing from position x1 to position x2 is called a displacement Δx, where Δx = x2 - x1.

Note: Δ is a symbol used for representing change in quantity. Displacements to the right are always positive and to the left negative.

Example: A particle moves from x1= 5m to position x2 = 15m gives Δx = 15m - 5m.= 10m (a positive displacement); however a particle moving from x1= 15m to position x2 = 5m = 5m - 15m.= -10m (a negatve displacement)

The actual distance of the trip is irrelevant - it is only the original and final position that count.

Ignoring the sign of the displacement changes it from the vector (displacement) to a scalar (distance); while the magnitudes are the same the direction is very important and distinguishes vector from scalar quantities.


Calculate the displacements in the following displacements:
(a) - 4m to 26m (b) 64m to 23m (c) -6m to 10m (d) -4m to -20m (e) -10m to -5m.

Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.