Question

· A sound wave has frequency of 2 kHz and
wavelength of 35 cm. If an observer is
1.4 km away from the source. At what
time interval could the observer hear the
sound?
(a) 2s (b) 20 (c) 0.55 (d) 45
​

Answer 1

Answer:

It will take 2 second to travel 1.5 km.

Explanation:

Given,

Frequency = f = 2kHz = 2000 Hz

Wavelength = λ = 35 cm = 35 / 100 m

To find: How long will it take to travel 1.5 km

Solution:

Concept: Wave speed is defined as the product of wavelength and frequency.

i.e v = λf

here, λ = 35/100 m and f = 2000 Hz

Substituting the values,

v = 35/100* 2000 = 700 m /s

So, Speed of sound wave is 700 m/s

Then, Time taken to travel the distance of 1.4 km = 1400 m will be:

Time taken = distance travelled / wave velocity

or, t = 1400 / 700 = 2 seconds

Therefore, it will take 2 second to travel 1.5 km.

Answer 2

Answer:

It take 2s in 1.5km.......✨