Calculate Average Velocity for Suzy's Jog

[VenaCava]

When calculating an average velocity in a problem containing multiple velocities each occurring for different lengths of time, would I be correct in calculating the total displacement and then dividing by the total time?

For example:
Suzy goes for a jog one day. She runs at an average velocity 3 m/s north for 2 minutes and then an average velocity of 5m/s south for 3 minutes. What is her average velocity?
I believe it would be solved like this:

d=vt = (3m/s)(120s) =360m
d=vt = (-5m/s)(180s)=-900m

total d = 360m + (-900m) =-540m
total t =300s

Average V = -540m/300s = -1.8m/s

Thank you.

 

[LowlyPion]

When calculating an average velocity in a problem containing multiple velocities each occurring for different lengths of time, would I be correct in calculating the total displacement and then dividing by the total time?

For example:
Suzy goes for a jog one day. She runs at an average velocity 3 m/s north for 2 minutes and then an average velocity of 5m/s south for 3 minutes. What is her average velocity?
I believe it would be solved like this:

d=vt = (3m/s)(120s) =360m
d=vt = (-5m/s)(180s)=-900m

total d = 360m + (-900m) =-540m
total t =300s

Average V = -540m/300s = -1.8m/s

Thank you.

Welcome to PF.

Velocity is treated as a vector and that's right.
Average speed would have been different, but I think you know that already.

Good luck.

 

[baba89]

Your calculation and approach are correct. When calculating average velocity, we must consider the total displacement and the total time taken to cover that displacement. In this case, Suzy's total displacement is -540m (since she is moving in opposite directions, we use negative values for the south direction) and her total time is 300s. Therefore, her average velocity is -1.8m/s. It is important to note that average velocity is a vector quantity, meaning it has both magnitude and direction. So in this case, Suzy's average velocity is in the south direction with a magnitude of 1.8m/s.