$2)$ As shown in the next Figure, water is pumped into a tall, vertical cylinder at a volume flow rate R $[$L$/$min$].$ The radius of the cylinder is r $[$cm$],$ and at the open top of the cylinder a tuning fork is vibrating with a frequency f$[$Hz$].$ The sound speed is assumed to be V $[$m$/$s$].$ As the qater rises, what time interval elapses between successive resonances?