While walking between gates at an airport, you notice a child running along a mo
ID: 1708699 • Letter: W
Question
While walking between gates at an airport, you notice a child running along a moving walkway. Estimating that the child runs at a constant speed of 2.2 m/s relative to the surface of the walkway, you decide to try to determine the speed of the walkway itself. You watch the child run on the entire 23-m walkway in one direction, immediately turn around, and run back to his starting point. The entire trip takes a total elapsed time of 33 s. Given this information, what is the speed of the moving walkway relative to the airport terminal?m/s
Need answer before 1:00 PST
Explanation / Answer
let x=speed of walkway
then (2.2+x)= speed of child moving in direction of walkway
then (2.2-x)= speed of child moving against direction of walkway
Travel time=distance/speed
travel time of child moving in direction of walkway=23/(2.2+x)
travel time of child moving in direction of walkway=23/(2.2-x)
total elapsed time given=33 s
23/(2.2+x)+23/(2.2-x)=33
LCD=(2.2+x)(2.2-x)
23(2.2-x)+23(2.2+x)=33(2.2+x)(2.2-x)
23*2.2-23x+23*2.2+23x=33(2.2^2-x^2)
23(2.2+2.2)/33=2.2^2-x^2
x^2=(2.2)^2-(23*4.4)/33)=1.773333333
x=sqrt(1.773333333)= 1.331665624 m/s
ans: Speed of walkway= 1.331665624 m/s
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