Multiple choice: An athlete runs 70 meters from A to B in a straight line at a speed of 2 m/s and then back from B to A at a speed of 4 m/s. What is true about the average speed and the average velocity of the runner?

A. speed = 2.66, velocity = 2.66
B. speed = 3, velocity = 0
C. speed = 0, velocity = 0
D. speed = 2.66, velocity = 0

Please answer AND explain. thank you.

Question

Multiple choice: An athlete runs 70 meters from A to B in a straight line at a speed of 2 m/s and then back from B to A at a speed of 4 m/s. What is true about the average speed and the average velocity of the runner? 

 A. speed = 2.66, velocity = 2.66 
 B. speed = 3, velocity = 0 
 C. speed = 0, velocity = 0 
 D. speed = 2.66, velocity = 0 

Please answer AND explain. thank you.

anonymous · Answer

to make things a bit easier B is NOT correct

anonymous · Answer

@hartnn could you answer and explain this? Thank you.

hartnn · Answer

ok, average speed of s1 and s2 will be 
$Average = 2 s_1s_2/(s_1+s_2)$
here , s1= 2, s2 = 4

hartnn · Answer

and average velocity = displacement/ time
here , displacement = 0 because the athelete comes back to same position

anonymous · Answer

thanks ! I understand now.

hartnn · Answer

welcome ^_^