I would say D because when you think about tug-of-war, when someone on one side lets go, the people on the other team are able to pull the rope further to their side. So the rope would move right to the side of the red team because someone on the blue team let go therefore, there is less balancing the rope on the blue teams side.
Wavelength = (speed) / (frequency)
Wavelength = (8 m/s) / (2/s)
Can you finish it off from this point ?
Answer:
Explanation:
Given
A is the area of circle with radius r
Differentiate w.r.t time
Also 
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