Their average velocity is 0.98 m/s east.
Explanation:
The average velocity of an object is defined as the ratio between the displacement and the time taken:
The displacement is a vector connecting the initial point to the final point of motion: so, being displacement a vector, velocity is a vector as well, having the same direction of displacement.
Here, Heather and Matt walk 2.0 km eastward, so their displacement is
d = 2.0 km = 2000 m (east)
While the time they took is
Therefore, their average velocity is
And the direction is the same as the displacement (east).
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