An object travels North at #15 m/s# for #3 s# and then travels South at #12 m/s# for #7 s#. What are the object's average speed and velocity?

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Answer 1 · 2017-06-29T05:26:34

The average speed is #=12.9ms^-1#
The average velocity is #=-3.9ms^-1#

The total distance travelled is #d=15*3+12*7=129m#

The total time is #t=3+7=10s#

The average speed is

#barv=d/t=129/10=12.9ms^-1#

The displacement is

#Deltax=15*3-12*7=-39m#

The average velocity is

#=(Deltax)/t=-39/10=-3.9ms^-1#