Question:
A circular road of radius $50 \mathrm{~m}$ has the angle of banking equal to $30^{\circ}$. At what speed should a vehicle go on this road so that the friction is not used?
Solution:
$\tan \theta=\frac{v^{2}}{R g}$
$\tan 30^{\circ}=\frac{v^{2}}{(50)(10)}$
$\mathrm{v} \cong 17 \mathrm{~m} / \mathrm{s}$