Walking Speed
\[l\]
is \[T=2 \pi \sqrt{\frac{l}{g}}\]
so the frequency is \[f= \frac{1}{T} =\frac{1}{2 \pi} \sqrt{\frac{g}{l}} \]
.If someone with a leg of length
\[l\]
takes \[f\]
strides per second, swinging their leg through an angle of 30 ° each time, then the distance moved in one stride is \[d=l \theta\]
and the distance moved in one second, the speed, is \[v=df=l \theta \frac{1}{2 \pi} \sqrt{\frac{g}{l}} = \frac{\theta}{2 \pi} \sqrt{lg}\]
.The length of a leg is about 0.9m and a person may swing their leg through an arc of 39°' or
\[\frac{\pi}{6}\]
.\[v=df= \frac{\theta}{2 \pi} \sqrt{lg}=\frac{\pi/6}{2 \pi} \sqrt{0.9 \times 9.8}= 0.25 m/s\]
.This is only an approximation. A comfortable walking speed is about 3 miles per hour or
\[\frac{3 \times 1609}{3600}= 1.34 m/s\]
. 
