Displacement and distance…what’s the difference



Displacement and distance…what’s the difference?

Distance is a scalar quantity—it has magnitude only, a positive numerical value, with units . Displacement is a vector quantity—it has direction as well as magnitude.

Displacement is the change in position of an object. In other words, it is a comparison of where an object ends up to where it started: how far away, and in what direction.

For a simple trip, the only difference from distance is that displacement includes direction.

ex. You walk 5 meters in the northward direction. Distance = 5m,

displacement = 5m north.

For multi-part trips, the difference between total distance traveled and net displacement is more significant.

ex. You walk 5 meters north and turn

and walk 5 meters east. You are now

[pic]meters from where you started,

in the northeast direction. By contrast,

the total distance you walked is 10 meters.

Questions: For each, figure out the total distance traveled, and the net displacement.

1. 5m north, then 2m east.

2. 6m south, then 3m east, then 6m north

3. 5m up, then 10m north, then 5m down

4. 5m west, then 12m north

5. 2m east, then 3m north, then 4m west

6. 10m east, then 2m north, then 8m west

7. 6m east, then 5m east

8. 1m north, then 1m east, then 1m south, then 1m west

9. A squirrel runs 5m north to an oak tree, scampers straight up the trunk to a height of 4m, then saunters out onto a southward-headed branch a distance of 2m.

10. A runner runs around a circular track exactly 4 times. The track has a radius of 63.7 meters.

challenge: A bug crawls 3m north, then 4m west, then 12m up (think of a room which is 3 x 4 x 12).

-----------------------

5m

Net displacement

5m

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