v = f l

2. 1. 0.1 ms^-1
   2. 0.9 ms^-1
   3. 3 ms^-1
   4. 30 000 000 ms^-1
3. 1. 471428.6 Hz
   2. 495.7 Hz
   3. 8.5 Hz
   4. 1.5 Hz