A small charge q$=0\mathrm{.}1$ nC is placed distance $3\mathrm{.}9$ cm away from a stationary charge Q$=4\mathrm{.}9$ nC$.$ At that spot charge q experiences acceleration of magnitude $564$ m$/$s$2.$ What is the mass of the charge q$?$

Express your answer in kilograms, use scientific notation. On TH$,$ the scientific notation follows a format x$.$yzEn where x$.$yz is the number expressed with a precision of three significant figures, E indicates the exponent and n is the power of the exponent.