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

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

An object travels North at 15 m/s15 m/s for 3 s3 s and then travels South at 12 m/s12 m/s for 7 s7 s. What are the object's average speed and velocity?