SOLUTION: Supposed flying in a calm air a robin can reach a speed of 25 kilometers per hour. Each day, this robin flies from its nest to the nearest body of water 1 kilometer away. On one pa
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Question 1138663: Supposed flying in a calm air a robin can reach a speed of 25 kilometers per hour. Each day, this robin flies from its nest to the nearest body of water 1 kilometer away. On one particular day it flew into a headwind and on its return trip the wind was at it's back. if the total trip took 1/10 of an hour, what was the speed of the wind? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! Supposed flying in a calm air a robin can reach a speed of 25 kilometers per hour.
Each day, this robin flies from its nest to the nearest body of water 1 kilometer away.
On one particular day it flew into a headwind and on its return trip the wind was at it's back.
if the total trip took 1/10 of an hour, what was the speed of the wind?
:
let w = the speed of the wind
then
(25-w) = the ground speed against the wind
and
(25+w) = the speed with
:
Write a time equation; time = dist/speed
to lake time + return time = .1 hr + = .1
multiply equation by (25-w)(25+w), cancel the denominators
(25+w) + (25-w) = .1(25-w)(25+w)
25 + 25 + w - w = .1(-w^2 + 625); difference of squares
50 = -.1w^2 + 62.5
.1w^2 = 62.5 - 50
.1w^2 = 12.5
multiply both sides by 10
w^2 = 125
w =
w = 11.18 km/hr is the speed of the wind
:
:
Check this, find the actual time each way = .0724 hrs = .0276 hrs
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round trip time: = .1000 hrs
