# An object travels North at 9 m/s for 5 s and then travels South at 7 m/s for  3 s. What are the object's average speed and velocity?

Dec 11, 2016

Average Speed: $8.25$ m/s
Average Velocity: $3$ m/s North

#### Explanation:

$9 \frac{m}{s} N$ for $5$ s
$\rightarrow$ distance traveled: $45 m$; displacement: $45 m N$

$7 \frac{m}{s} S$ for $3$ s
$\rightarrow$ distance traveled: $21 m$; displacement: $21 m S$

Total Distance traveled for $8$ s: $45 + 21 m = 66 m$
Average Speed: $66 m$ / $8 s = 8.25 m \text{/} s$

Total Displacement after $8$ s: $45 m N - 21 m S = 24 m N$
Average Velocity: $24 m N \text{/"8 s=3m"/} s N$