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An object travels North at # 8 m/s# for #8 s# and then travels South at # 3 m/s# for # 7 s#. What are the object's average speed and velocity?

Answer 1

Elena Albarran

Average speed = 5.7 m/s

Average velocity = 2.9 m/s

Distance along north#= "8 m"/cancel"s" × 8 cancel"s" = "64 m"#

Distance along south#= "3 m"/cancel"s" × 7 cancel"s" = "21 m"#

"64 m + 21 m" = "85 m" is the total distance.

Displacement#= "64 m North" - "21 m South" = "43 m North"#

Average speed#= "Total distance"/"Time" = "85 m"/"8 s + 7 s" = "5.7 m/s"#

Average velocity#= "Displacement"/"Time" = "43 m"/"8 s + 7 s" = "2.9 m/s"#

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Answer 2

Leo Abeyta

The object's average speed is ( 5.75 , \text{m/s} ) and its average velocity is ( 2.25 , \text{m/s} ) south.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.