Q$6.$ An object undergoes simple harmonic motion along an $x$ axis with a period of $0\mathrm{.}25$ s and amplitude of $35$ mm $.$ Its position is $x=-13mm$ when $t=0s.$ Keep $0{}_{i}2($a$)$ Write an equation showing the object's displacement with all the variables identified. Hint: two possible initial phases $($use radians$),$ why?

$($b$)$ Draw a position$-$versus$-$time graph for this motion.