$(15$ Points$)$ A sinusoidal wave in a rope is described by the wave function y$=0\mathrm{.}20$sin$(0\mathrm{.}75\backslash$pi x$+18\backslash$pi t$)$ where x and y are in meters and t is in seconds. The rope has a linear mass density of $0\mathrm{.}25$ k$($g$)/($m$).$ The tension in the rope is provided by a table$-$top pulley and mass setting fixed inside an elevator, as illustrated in figure below. The acceleration of the elevator is indicated in the figure. $($a$)(5$ points$)$ What is the wave speed of the wave? $($b$)(10$ points$)$ What is the mass of the mass block m$?$

$(15$ Points$)$ A sinusoidal wave in a rope is described by the wave function

y$=0\mathrm{.}20$sin$(0\mathrm{.}75\backslash$pi x$+18\backslash$pi t$)$ where x and y are in meters and t is in seconds.

The rope has a linear mass density of $0\mathrm{.}25$k$($g$)/($m$).$ The tension in the rope

is provided by a table$-$top pulley and mass setting fixed inside an

elevator, as illustrated in figure below. The acceleration of the elevator is

indicated in the figure.

$($a$)(5$ points$)$ What is the wave speed of the wave?

$($b$)(10$ points$)$ What is the mass of the mass block m $?$