TRUE$/$FALSE

Polar coordinates coincide with normal and tangential coordinates only when the path followed by a particle is circular.

$a_r=v_r^{}$ and $a_{}=v_{}^{}.$

$a_{}=r^{}-r{}^2{?}^{}.$

$\frac{1}{r}\frac{d(r^2({}^{}))}{dt}=2r^{}{}^{}+r{}^{}.$

The curvature of a circle is equal to its radius.

A particle is moving along a circular path having a radius of $6$ inches such that its position as a function of time is given by $=cos(3t),$ where $$ is in radians and $t$ is in seconds. Find the acceleration of the particle when $=30.$ The particle starts from rest when $=0^0.$