A motor produces a transverse wave along a row of connected rods in a wave machine. A sensor records 36 complete oscillations at one position during 1.8 s. A 0.75 m section has a trough at its left-hand end and a crest at its right-hand end. It also contains two crests between its ends.
What is the speed of the wave?
6.0 m/s6.0\ \mathrm{m/s}6.0 m/s
10 m/s10\ \mathrm{m/s}10 m/s
4.3 m/s4.3\ \mathrm{m/s}4.3 m/s
7.5 m/s7.5\ \mathrm{m/s}7.5 m/s