An object travels North at #8 m/s# for #4 s# and then travels South at #6 m/s# for #7 s#. What are the object's average speed and velocity?

1 Answer
Aug 28, 2017

Answer:

Average speed: #6 8/11 m/s#

Average velocity: #10/11 m/s " South"#

Explanation:

#{: (,ul("Distance"),color(white)("xxx"),ul("Displacement")), ("first 4 seconds",8m/sxx4s=32m,,8m/s N xx4s =32 m N), ("second 7 seconds",6m/sxx7s=42m,,6m/s Sxx7s=42 m S) :}#
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Total time: #4 s + 7 s=11s#

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Total distance: #=32 m + 42 m = 74m#

Average speed: #"distance"/"time"=(74 m)/(11 s)=6 8/11 m/s#

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Total displacement: #32 m color(red)N +42 m S#
#color(white)("XXXXXXXXXXXXXXXXXX")=color(red)-32m color(red)S +42 m S#
#color(white)("XXXXXXXXXXXXXXXXXX")=10 m S#

Average velocity: #"displacement"/"time"= (10 mS)/(11s)=10/11 m/s S#