A smooth marble dropped from a height $\backslash ($ h $\backslash )$ achieves a speed of $\backslash ($ v $\backslash )$ by the time it reaches the ground $($neglecting air resistance$).$ At what height $($relative to h$)$ should the same marble be dropped to achieve a speed of $2$ v just before reaching the ground?$2$ times h $\mathrm{.}4$ times hImpossible to tell without knowing h and v $.$hetimes the enuare rout of$?$