Understanding Distance and Displacement

Understanding Distance and Displacement

Open Ended

What do you think Physics is?

Questions for consideration

• What is distance?

• How is displacement different from distance?

Distance

• Distance (d)- how far an object travels.

• Does not depend on direction.

Distance

• Imagine an ant crawling along a ruler.

• What distance did the ant travel?

• d = 3cm

Distance

• Here's our fearless ant explorer again.

• Now what distance did the ant travel?

Multiple Choice

Now, what distance did the ant travel?

• d = 3 cm

• d = 5 cm

• I don't know

Let's follow the ant again.

• What distance did it walked this time?

Multiple Choice

What distance did it walk this time?

• d = 7cm

• d = 5cm

• d = 2cm

• I don't know

Distance

• The ant walked 7cm.

• Why?

• d = 5cm + 2cm = 7cm.

Displacement

• Difference between an object's final position and its starting position.

• DOES depend on direction.

• Displacement= final position - initial position.

Displacement

• In order to define displacement, we need directions.

• Some examples of directions are:

• + and -

• N, S, E, W

Displacement vs. Distance

• Examples of distance:

• The ant walked 3cm

• Example of displacement:

• The ant walked 3cm EAST

• Important: an object's distance traveled and its displacement isn't always the same!

Displacement

• Let's revisit our ant, and this time we'll find his displacement.

• Distance = 3cm

• Displacement = 3+ cm

• The positive gives the ant a direction!

• 
  

Multiple Choice

Find the ant's displacement again. Remember displacement has direction!

• Displacement = -3cm

• Displacement = +3m

• Displacement = -2cm

• I don't know

Displacement

• Distance = 3cm

• Displacement = -3cm

Open Ended

Find the distance and displacement of the ant.

Distance vs Displacement

• Distance = 7 cm

• Displacement = +cm

Displacement vs. distance

• An athlete runs a track that is 100 meters long three times, then stops where he began.

• What is the athlete's distance and displacement?

Multiple Choice

An athlete runs around a track that is 100 meters long three times. What is the athlete's distance?

• 300 meters

• 100 meters

• I don't know

Multiple Choice

What is the athelete's displacement?

• 0

• 300 meters