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?

Question

anonymous · Answer

:/

anonymous · Answer

30/8

lgbasallote · Answer

15 meters?

lgbasallote · Answer

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

shubhamsrg · Answer

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

anonymous · Answer

4m/s

lgbasallote · Answer

so it will be 30/8 seconds?

anonymous · Answer

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

lgbasallote · Answer

i mean m/s

lgbasallote · Answer

what does harmonic mean mean again?

anonymous · Answer

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

kropot72 · Answer

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

lgbasallote · Answer

where a and b are...?

lgbasallote · Answer

the given values?

cwrw238 · Answer

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

anonymous · Answer

a=5 and b =3 or vice-versa

anonymous · Answer

its 3.75 m/s 4 is wrong

anonymous · Answer

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

lgbasallote · Answer

this is effective everytime d is equal?

anonymous · Answer

total distance /total time travelled

anonymous · Answer

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

lgbasallote · Answer

arithmetic mean is..?

anonymous · Answer

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

anonymous · Answer

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

lgbasallote · Answer

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?

anonymous · Answer

yeah it is zero

shubhamsrg · Answer

yes,,because disp is 0..

anonymous · Answer

but its speed written in the question???

lgbasallote · Answer

the first question was average speed

anonymous · Answer

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

anonymous · Answer

distance adds up*

anonymous · Answer

lol really? at 5m/s ?

lgbasallote · Answer

what? o.O

anonymous · Answer

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