Fig. P$13\mathrm{.}70$ and P$13\mathrm{.}71$

$13\mathrm{.}71$ A roller coaster starts from rest

at $A,$ rolls down the track to $B,$

describes a circular loop of $12-$

m diameter, and travels up and

down past point $E.$ Determine

the range of values of $h$ for

which the roller coaster will

not leave the track at $D$ or $E.$

Assume no energy loss due to

friction.