Translations:Ray equation for velocity linear with depth/29/en

${\begin{aligned}{\frac {d\theta }{ds}}&{\rm {=}}{\frac {a{\rm {\ sin\ }}\theta }{v}}{\rm {=}}ap{\rm {=}}{\frac {a{\rm {\ sin\ }}{\theta }_{0}}{v_{0}}}.\end{aligned}}$

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