Final answer:
The sound wave travels at a speed of 700 m/s, and it would take approximately 2.1 seconds to travel a distance of 1.5 km.
Step-by-step explanation:
To determine how long it takes for a sound wave with a frequency of 2 kHz and a wavelength of 35 cm to travel a distance of 1.5 km, we need to calculate the speed of the sound wave first. The speed v of a wave is given by the product of its frequency f and its wavelength λ, or v = f × λ. In this case, the sound wave has a frequency f of 2 kHz (which is 2000 Hz) and a wavelength λ of 35 cm (which is 0.35 m). Thus, the speed of the sound wave is 2000 Hz × 0.35 m = 700 m/s. To find the time t it takes to travel 1.5 km (which is 1500 m), we use the formula t = d/v, where d is the distance the wave travels. Plugging in the values, we get t = 1500 m / 700 m/s = 2.14 s. This can be rounded to 2.1 seconds, which means the correct answer is (d) 2.1 sec.