Answer:
Average speed = 1.4 m/s
Average velocity = 0.79 m/s East
Explanation:
Average velocity is the total displacement divided by the total time, where displacement is the difference in the final and initial positions. By comparison, average speed is the total distance divided by the total time, where distance is the length of the path traveled. Velocity and displacement are vectors (magnitude and direction), whereas speed and distance are scalar (magnitude only).
First, find the total time the dog moves. Time is equal to distance over speed:
t = d / v
When walking, the time is:
t = 12 m / (1.3 m/s) = 9.23 s
When running, the time is:
t = 3.5 m / (2.2 m/s) = 1.59 s
The total time is:
9.23 + 1.59 = 10.82 s
The distance traveled by the dog is 12 + 3.5 = 15.5 m. The dog's average speed is:
v = 15.5 m / 10.82 s
v = 1.4 m/s
Next, find the dog's displacement, taking East to be positive and West to be negative.
When walking, the displacement is +12 m. When running, the displacement is -3.5 m. The total displacement is 12 − 3.5 = 8.5 m East.
The dog's average velocity is:
v = 8.5 m East / 10.82 s
v = 0.79 m/s East
