Collar Cis pushed along the guide bar defined by $y=2(1-0\mathrm{.}25x^2),$ where $x$ and $y$ have units of meters. The angular speed of arm $AB$ that actuates the motion is the constami value $=19ra\frac{d}{s}$ counterclockwise $($see figure$).$

Find the magnitude of the acceleration of the collar at the instant when the arm $AB$ is horizontal $(=0).$

$722\mathrm{.}250$

Correct Answer: $744\mathrm{.}22$