## lgbasallote 3 years ago A person walks first at constant speed of 5.00 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 3.00 m/s. What is her average speed over the entire trip?

1. A.Avinash_Goutham

:/

2. A.Avinash_Goutham

30/8

3. lgbasallote

15 meters?

4. lgbasallote

why not just 1? i mean it's simpler isnt it?

5. shubhamsrg

total dist = 2d total time = d/5 + d/3 = 8d/15 so avg speed = 2d/(8d/15) so @A.Avinash_Goutham was right!! yet again! :D

6. Nick_Black

4m/s

7. lgbasallote

so it will be 30/8 seconds?

8. FoolForMath

When the distance is fixed, just find the harmonic mean.

9. lgbasallote

i mean m/s

10. lgbasallote

what does harmonic mean mean again?

11. FoolForMath

For two number a and b the harmonic mean is given by 2ab/(a+b)

12. kropot72

Speed = (distance traveled)/(time taken) Total distance traveled = 0 Speed = 0 m/s

13. lgbasallote

where a and b are...?

14. lgbasallote

the given values?

15. cwrw238

speed = distance / time if distance = 1 5 = 1 / 0.2 also 3 = 1 / 0.3333 average speed = 2 / 0.53333

16. FoolForMath

a=5 and b =3 or vice-versa

17. Nick_Black

its 3.75 m/s 4 is wrong

18. A.Avinash_Goutham

if it's equal " time " u shud use........arithmetic nd equal dist u shud use..........harmonic

19. lgbasallote

this is effective everytime d is equal?

20. Nick_Black

total distance /total time travelled

21. FoolForMath

Yes lgba and when time is equal find the arithmetic mean.

22. lgbasallote

arithmetic mean is..?

23. Nick_Black

2d ----------- d +d -- ---- 5 3 2d --------- 8d ------ 15 2 ---- 8 ------ 15

24. Nick_Black

2 ---- 8 --- 15 15 ---- 4

25. lgbasallote

lol yeah i got that part =)) btw...a follow-up question is what is the average velocity...the book says zero...is it because displacement is 0?

26. A.Avinash_Goutham

yeah it is zero

27. shubhamsrg

yes,,because disp is 0..

28. Nick_Black

but its speed written in the question???

29. lgbasallote

the first question was average speed

30. Nick_Black

yeah but there is a difference displacement can come to zero bot distance cannot u should mention adds up whether how many time come and go from same point asdisplacement get zero

31. Nick_Black

32. javawarrior

lol really? at 5m/s ?

33. lgbasallote

what? o.O

34. javawarrior

A person walks first at constant speed of 5.00 m/s <== that guy must be one heck of a power walker haha