A sound wave has frequency of 2 kHz and wavelength of 35 cm. If an observer is 1.4 km away from the source, after what time interval could the observer hear the sound?

The correct answer is Option 1 (2 s). This problem is solved using the fundamental relationship between frequency, wavelength, and speed of sound.

To find the time interval, we first calculate the speed of the sound wave using the formula: Speed (v) = Frequency (f) × Wavelength (λ).

• Frequency (f) = 2 kHz = 2000 Hz
• Wavelength (λ) = 35 cm = 0.35 m
• Speed (v) = 2000 × 0.35 = 700 m/s

Next, we calculate the time (t) taken to cover the given distance (d) using the formula: Time = Distance / Speed.

• Distance (d) = 1.4 km = 1400 m
• Time (t) = 1400 / 700 = 2 seconds

Thus, the observer hears the sound after 2 seconds. Options 2, 3, and 4 are incorrect because they result from improper unit conversions or calculation errors in the speed-distance relationship.