Problem $3(25$ points$)$

You discovered a new drug delivery method using polymeric micelles and want to track how the loaded micelle travels through the body. The loaded micelle starts with $V_x=3m\frac{m}{s},$ at $x=0,y=0$ at the injection site and moves along a path described by $y=0\mathrm{.}2x^2.$ You know that the x component of the micelle's acceleration is $x^{}=(3t)m\frac{m}{s^2}.$

A$)$ Determine the $x$ location of the particle at $t=4s$

B$)$ Determine the magnitude of the micelle's acceleration at $t=4s$