SOLUTION: I am having problems understanding word problems with the "uniform motion" equation. My biggest problem is setting up the equation.
EX:
The speed of a moving walkway is about
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EX:
The speed of a moving walkway is about
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Question 850495: I am having problems understanding word problems with the "uniform motion" equation. My biggest problem is setting up the equation.
EX:
The speed of a moving walkway is about 2.5 feet per second. Walking on the moving walkway, it takes Kim a total of 40 seconds to walk 50 feet with the movement of the walkway and then back against the movement of the walkway. What is Kim's normal walking speed?
I really don't know how to use the "moving walkway speed" in the equation or how to set up the equation to get a correct result. Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! The speed of a moving walkway is about 2.5 feet per second.
Walking on the moving walkway, it takes Kim a total of 40 seconds to walk 50 feet with the movement of the walkway and then back against the movement of the walkway.
What is Kim's normal walking speed?
:
Let w = his walking speed in ft/sec
then
(w+2.5) = speed walking with the walkway movement
and
(w-2.5) = speed walking against the walkway
:
Write a time equation: time = dist/speed
:
with time + against time = 40 sec + = 40
multiply (w-25)(w+2.5) to cancel the denominators
50(w-2.5) + 50(w+2.5) = 40(w-2.5)(w+2.5)
50w - 125 + 50w + 125 = 40(w^2 - 6.25)
100w = 40w^2 - 250
0 = 40w^2 - 100w - 250; a quadratic equation
simplify, divide by 10
4w^2 - 10w - 25 = 0
I had to use the quadratic formula to find w, the positive solution:
w = 4.045 ft/ sec is his walking speed
:
:
Check this; find the time taken to walk each way. = 7.64 sec = 32.36 sec
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round trip time: 40 sec
