PRACTICE / Wave superposition

Combine amplitudes with phase

Two waves at one point have displacements y₁ = (4 mm) sin(ωt) and y₂ = (4 mm) sin(ωt + 120°).

Find the amplitude of their sum.

1. A$4\ \mathrm{mm}$
2. B$8\ \mathrm{mm}$
3. C$0\ \mathrm{mm}$
4. D$4\sqrt2\ \mathrm{mm}$

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