Two Horizontal Curves on a Bobsled Run Are Banked at the Same

Multiple Choice

Two horizontal curves on a bobsled run are banked at the same angle, but one has twice the radius of the other. The safe speed (for which no friction is needed to stay on the run) for the smaller radius curve is v . What is the safe speed on the larger-radius curve?

A) $v / 2$
B) $v \sqrt { 2 }$
C) $v / \sqrt { 2 }$
D) $2 v$