Question

A cyclist knows the total mass of her self and her bicycle. She also knows how far she can coast when slowing down from a given speed. How could she use this information to determine the average resistance opposing her motion?

Answer 1

let $m$ - total mass of cyclist and bicycle

$v$ - given speed from which she is slowing down

$l$ - distance when she is slowing down

we need to determine average resistance $\mu$

from the conservation law of energy: ${\frac {mv^2} 2}=\mu mgl$

then $\mu= {\frac {v^2} {2gl}}$