Question

A compound string is made by fusing together two wires of different lengths, but of the same radius. Their densities are ρ 1 and ρ 2, where ρ 1 < ρ 2. The string is plucked at the end of the ρ 1 wire. At the interface, part of the pulse is reflected, while the other part is transmitted. The transmitted and reflected pulses reach their respective ends at the same time.

1. Draw snapshots of what the string looks like at t=0 when the pulse is started, immediately before and after the pulse reaches the interface between the two materials, and when both pulses reach their ends.
2. What percentage of the string should be made of ρ 1 for both transmitted and reflected waves to reach their respective ends at the same time?

Answer 1