Answer: Steel.
- A Air
- B Water
- C Steel
- D All at same speed
Correct answer: C. Steel
Explanation: Sound travels fastest in solids (steel ~5100 m/s) because particles are closely packed with strong bonds.
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.