Waves P and Q arrive together at point X and superpose. At first, the two waves reach X in phase (zero phase difference), giving a resultant wave amplitude of $14.0\,\text{cm}$ at that point. The phase difference between the two waves is then altered so that, at X, they have a phase difference of $180^\circ$. The resultant wave now has an amplitude of $4.0\,\text{cm}$ at X. What is the amplitude of one wave at point X?
- A$2.0\,\text{cm}$
- B$5.0\,\text{cm}$
- C$10\,\text{cm}$
- D$18\,\text{cm}$