posted by JC .
A cyclist in an Olympic race is moving in a circular track of radius 80 m with speed 72 km/h. He has to lean from the vertical approximately through an angle of...
How is tan-1(1/2) derived in this answer?
draw a sketch of the cyclist.
notice from her center of gravity, a horizontal force (centripetal force) of mv^2/r
the vertical force is mg
so tan Theta= mv^2/mgr=v^2/gr
now, the numbers v=72km/hr=20m/s (how convenient ) , and r=80