1. The problem statement, all variables and given/known data A sinusoidal wave is propagating along a stretched string that lies along the x-axis. The displacement of the string as a function of time is graphed in the figure (attachment) for particles at x=0m and x=0.0900m. (A) What is the amplitude of the wave? 4mm (B) What is the period of the wave? 0.04s (C) You are told that the two points x=0 an x=0.09m are within one wavelength of each other. If the wave is moving in the +x-direction, determine the wavelength and wave speed. ANSWER KEY: 0.14m and 3.5m/s I am confused about this part: (D) If the wave is moving in the -x-direction, determine the wavelength and wave speed. ANSWER KEY: 0.24m and 6.0m/s (e) Would it be possible to determine definitively the wavelength in parts (c) and (d) if you were not told that the two points were within one wavelength of each other? Why or why not? NO 2. Relevant equations y(x,t)=Acos(kx +/- ωt) v=λf 3. The attempt at a solution Apparently, for part d, they did 0.09 m / 0.015 s to get the velocity and I'm not sure how they got 0.015s for the time when it's moving in the negative x-direction. You get this time if the peak of x=0 shifts to t=0.05 s because it's travelling in the opposite direction so the peak of x=0 comes before x = 0.09, and then you do 0.05-0.035 to get this? Is this right?