A rope, under tension of $200 \mathrm{~N}$ and fixed at both ends, oscillates in a second harmonic standing wave pattern. The displacement of the rope is given by $y=(0.10 \mathrm{~m}) \sin \left(\frac{\pi x}{2}\right) \sin (12 \pi t)$, where $x=0$ at one
end of the rope, $x$ is in metres, and $t$ is in seconds. Find
(A) the length of the rope
(B) the speed of waves on the rope
(C) the mass of the rope
(D) if the rope oscillates in a third harmonic standing wave pattern, what will be the period of oscillation?