A girl runs 40m due south in 40 seconds an d then 20m due north in 10 secondsCalculate. the average speed,
her average velocity .
in her change in velocity for the whole journey!​

Average speed = 1.2 m/s

Average velocity = 0.4 m/s

Explanation:

Average speed = total distance/total time

Average speed = (40 + 20)/(40 + 10)

Average speed = 60/50

Average speed = 1.2 m/s

Average velocity = displacement/time

Now, she ran 40 m south and ran 20 m back north which is in the direction of where she began the journey.

Thus;

Displacement = 40 - 20 = 20 m

Average velocity = 20/50 = 0.4 m/s

pe = weightxheight = 2000x1000=2,000,000joules