Average Walking Speed

Question

The speed of a moving walkway is about 3.5 feet per second. Walking on the moving walkway, it takes Kim a total of 20 seconds to travel 35 feet with the movement of the walkway and then back against the movement of the walkway What is Kim’s normal walking speed?

Answer 1

distance = speed x time

one half trip = 35/2 = 17.5 = (3.5+v)(t)

back half trip = 17.5 = (3.5-v)(20-t)

v = Kim's normal walking speed 20 = total time both ways t = time walking with the moving walkway

20-t = time walking against the moving walkway

take those two equations 17.5=(3.5+v)t and 17.5=(3.5-v)(20-t)

expand them, add or subtract them to get v in terms of t or vice versa

then substitute back into either of the original equations to get a

quadratic equation in terms of one variable only. Use the quadratic formula

Answer should be less than 3 for t, and about 2.5 ft/sec for Kim's normal walking speed

2.5+3.5 = 6 ft/sec one way, then 3.5-2.5=1 ft/sec the other way

17.5= about 6 times 2.9 seconds 17.5 = 1 times 17.5 seconds

These calculations have some rough approximations, but gives the general ball park solution