Distance vs Displacement Learning Target l I can

Distance vs Displacement

Learning Target l I can explain the difference between distance and displacement. l Why? l In this unit we will be investigating distance compared to displacement. You should be able to say how they are different and how they are the same.

Distance l Distance (d) – measures how far an object travels. l It l 0 cm l does not depend on direction. Imagine an ant crawling along a ruler. 1 2 3 4 5 6 7 8 What distance did the ant travel? ld = 3 cm 9 10

Distance l l Distance measures how far an object travels but isn’t dependent on direction. Here’s our intrepid ant explorer again. 0 cm l l 1 2 3 4 5 6 7 8 Now what distance did the ant travel? l d = 3 cm Does his direction change the answer? l No 9 10

Distance l l 0 cm l l Distance does not depend on direction. Let’s follow the ant again. 1 2 3 4 5 6 7 8 9 What distance did the ant walk this time? d = 7 cm 10

Displacement l Displacement – is the difference between an object’s final position and its starting position. l It does depend on direction.

Displacement vs. Distance l Example of distance: l The l Example of displacement: l The l ant walked 3 cm EAST. An object’s distance traveled and its displacement aren’t always the same!

Displacement Calculation l l Displacement = final position – initial position x = xfinal – xinitial In order to define displacement, we need directions. Examples of directions: l l Positive (+) and negative (–) North, South, East, West

Displacement l Let’s revisit our ant, and this time we’ll find his displacement. - + 0 cm 1 2 3 4 5 6 7 8 Distance: 3 cm l Displacement: +3 cm l l The positive gives the ant a direction! 9 10

Displacement l Find the ant’s displacement again. l Remember, displacement has direction! - + 0 cm 1 2 3 4 5 Distance: 3 cm l Displacement: -3 cm l 6 7 8 9 10

Displacement l Find the distance and displacement of the ant. - + 0 cm 1 2 3 4 5 Distance: 7 cm l Displacement: +3 cm l 6 7 8 9 10

Displacement vs. Distance l An athlete runs around a track that is 100 meters long three times, then stops. l What is the athlete’s distance and displacement? l l l Distance = 300 m Displacement = 0 m Why?