Question 498778
Let {{{c}}} = rate of child on stationary sidewalk
Let {{{s}}} = rate of moving sidewalk
Let {{{d}}} = length of the sidewalk
Let {{{t}}} = time spent on moving sidewalk
given:
Running against motion of sidewalk
{{{ d = ( c - s )*t }}}
Running with motion of sidewalk
{{{ d = ( c + s )*t }}}
The distance and the time are the same in both cases
{{{ c - s = c + s }}}
{{{ -s = s }}}
{{{ 2s = 0 }}}
The sidewalk is not moving