Take the starting position 113 m above ground to be the origin, and the downward direction to be positive. Then the vertical position [tex]y[/tex] of the handkerchief (ignoring air resistance due to the absence of an atmosphere) at time [tex]t[/tex] is
[tex]y=\dfrac12gt^2[/tex]
where [tex]g[/tex] is the acceleration due to gravity on this moon. We have
[tex]113\,\mathrm m=\dfrac g2(18.2\,\mathrm s)^2\implies g=12.4\,\dfrac{\mathrm m}{\mathrm s^2}[/tex]
