Answer: 1000/(2pi) Hz; 1/(10pi) Hz.
- A 1000/(2pi) Hz; 1/(10pi) Hz
- B 500/pi Hz and 1/pi Hz
- C 159 Hz and 0.032 Hz
- D Both 159 Hz
Correct answer: A. 1000/(2pi) Hz; 1/(10pi) Hz
Explanation: y = amplitude-modulated wave. Frequency = 1000/(2pi) Hz. Amplitude varies at 1/(2 x 2pi x 10) = 1/(20pi) Hz.
A standing wave forms from two identical waves travelling in opposite directions and interfering; nodes (always zero displacement) and antinodes (maximum displacement) stay fixed in place, unlike a travelling wave where the whole pattern moves.
Concept context
Wave types, superposition, standing waves, Doppler effect, and sound intensity.