plug into the equation K=1/2mv^2 sooo.. (1/2)(.18)v(you don't have velocity so use the equation for potential energy because you haveheight)(U=mgh so (.18kg)(9.8m/s)(45)=U (set U equal to K)
(.18)(9.8)(45m)=1/2(.18)v^2
solve for v
don't forget to take the square root of v