An object travels North at #1 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 · 2018-03-01T06:41:52

See the explanation below

The total distance travelled is

#d=(1*3)+(12*7)=3+84=87m#

The total time is

#t=3+7=10s#

The average speed is #=d/t=87/10=8.7ms^-1#

The distance travelled is

#d_1=1*3-12*7=3-84=-81m#

The time is the same

#t=10s#

The average speed is

#=|d_1|/t=81/10=8.1ms^-1#