Tanvi leaves home and walks 3 km east, then 4 km north to the market…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Tanvi leaves home and walks east, then north to the market. After shopping, she walks west to a friend's house.
- At the market, how far has she walked, and how far is she from home?
- At her friend's house, how far has she walked, and how far is she from home now?
Need a reminder? The key ideaShow
Distance is the length of the whole path, a scalar. Displacement is the straight arrow from the start to the end, a vector. For two parts at right angles,
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. east, then north, then west.
Plan. Distance: add the lengths. Displacement: the straight arrow from home to where she is.
Step 1. At the market. Distance: . The two parts are at right angles, so the displacement is , at north of east.
Step 2. At the friend's house. Distance: . The east and the west cancel, so the displacement is due north.
Answer: (a) walked; displacement at north of east. (b) walked; displacement due north.
Check. Both times the displacement is less than the distance, as it must be.
Watch out. Walking farther made her displacement smaller. Distance can only grow, but displacement can shrink, or even become zero.
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