ANSWER: b

$2.$ A $0\mathrm{.}60-kg$ object is suspended from the ceiling at the end of a $2\mathrm{.}0-m$ string. When pulled to the side and released, it has a speed of $4\mathrm{.}0\frac{m}{s}$ at the lowest point of its path. What maximum angle does the string make with the vertical as the object swings up$?$

a$.61$

$(1)PE=KEmgh=\frac{1}{2}{m}_i{v}_i^2$