displacment & distance

a) The shope is 170m east from his home.

b)

Total displacement: 0
Total distance: 170 + 170 = 340m

2015-04-27 23:28:50 補充：
Corrections:

a) The shope is 160m east from his home.

b)

Total displacement: 0
Total distance: 160 + 160 = 320m

2015-04-27 23:29:23 補充：
Note:

Displacement is a vector --- take care about direction
As his whole journal does not move him from his original place to other places, displacement = 0

2015-04-27 23:32:51 補充：
Distance is a scalar --- only shows how long has one walked/travelled.
In this case obviously he has walked for 160×2m distance as he walked towards the shop and then straight to home with the same distance/path.

2015-04-27 23:33:48 補充：
Other examples include running along the common oval running track. After running for exactly 1 lap, you are back on your orginal place such that displacement = 0. However, in fact you have travelled for 400m and your total distance of this 1-lap trip is thus 400m.