## Essential University Physics: Volume 1 (3rd Edition)

We know that $t=\sqrt{\frac{2h}{g}}$ $t=\sqrt{\frac{2(0.196)}{9.8}}=0.2s$ As there are four drops at 0.2 seconds, the number of drops per second can be determined as $N=\frac{4}{0.2}=20 drops$