A sound wave travels through a glass sheet with a frequency of 2000 Hz and a wavelength of 2.5 m. It then passes into water, where the speed of sound is 1500 m/s.
Which gives the period of the wave in water and the percentage decrease in its wavelength?
6.7×10−4 s6.7\times10^{-4}\ \mathrm{s}6.7×10−4 s and 70%70\%70%
6.7×10−4 s6.7\times10^{-4}\ \mathrm{s}6.7×10−4 s and 30%30\%30%
5.0×10−4 s5.0\times10^{-4}\ \mathrm{s}5.0×10−4 s and 30%30\%30%
5.0×10−4 s5.0\times10^{-4}\ \mathrm{s}5.0×10−4 s and 70%70\%70%