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19 Jan 2011, 06:14
Kudos
Bookmarks
I know that average speed = total distance / total time
But can someone explain another formula I've found on this site:
average speed = (2ab)/(a+b)
a and b represent the average speed of each trip
Where does this come from?
Thanks!
But can someone explain another formula I've found on this site:
average speed = (2ab)/(a+b)
a and b represent the average speed of each trip
Where does this come from?
Thanks!
19 Jan 2011, 07:19
Kudos
Bookmarks
suesie970
I know that average speed = total distance / total time
But can someone explain another formula I've found on this site:
average speed = (2ab)/(a+b)
a and b represent the average speed of each trip
Where does this come from?
Thanks!
But can someone explain another formula I've found on this site:
average speed = (2ab)/(a+b)
a and b represent the average speed of each trip
Where does this come from?
Thanks!
Hey,
This formula is applicable when distances are equal.
example;
Mack travels half of his journey by train at the speed f 120 km/h ad rest half by car at 80 km/h. what is the average speed?
We can solve this problem by many ways.
1. Total distance,take LCM of 120 and 80 =240
therefore,time taken by train=120/120= 1 h
time taken by car = 120/80 = 3/2 h
Average speed = total distance/total time taken
=240/1+3/2
= 96 km/h
2.Method ;
Average speed=2xy/x+y ,where x and y are the speeds
Average speed= 2*120*80/120+80
= 96 km/h
I hope it helps you.
19 Jan 2011, 18:27
Kudos
Bookmarks
SoniaSaini,
Thanks for taking the time to respond. I understand how to use the formulas, I just would like to know where the second one comes from. That is, how was it derived?
Thanks for taking the time to respond. I understand how to use the formulas, I just would like to know where the second one comes from. That is, how was it derived?
