7 A cord has two sections, with linear densities of 0.10 kg/m and 0.20 kg/m respectively. A wave is incident from the lighter cord and is described by the equation D = 0.050 m sin (7.5x - 12.0t), where x is in meters and t is in seconds. What is the wavelength when the wave travels on the heavier section of the cord? Sketch the situation, defining all of your variables.

What physics equation(s) will you utilize in order to solve this problem? For each equation you list, give a justification for why it applies to this situation.

Apply your equation(s) to solve the problem as an algebraic expression(s).

Calculate your numerical answer(s). Show the units of your answer(s), and how you got them