Question

A sound wave has frequency of 2 khz and wave length of 35cm how will it take to travel 1.5 km?

Answer 1

Wavelength = λ = 35 cm = 0.35 m
Frequency = f = 2 kHz = 2000 Hz
We know,
v = f λ
v = 2000 × 0.35
   = 700 m/s
According to question:
we need to find time taken to travel 1.5 km   
We know 1 km = 1000 m
So, 1.5 km = 1500 m
Time taken = distance/speed or t = vd/v
                   = 1500/700
                   = 2.1428
∴ Time taken to travel 1.5 km = 2.1428 seconds

Answer 2

Hi there !!!

Here we are given the frequency as 2 kHz

We know that 1 kHz = 1000 Hz

So , 2kHz = 2000 Hz

Frequency, f = 2000 Hz

Also ,

Wavelength , λ = 35 cm

1 cm = 0.01 metres

So , Wavelength , λ = 0.35 metres

Here , in this question we are asked to find the time taken to cover the distance of 1.5 kilometres.

We know that 1 kilometre = 1000 metres

So ,
1.5 kilometre = 1500 metres

We know that ,
Velocity = frequency x Wavelength

= 2000 x 0.35

= 700 m/s

Also ,

Velocity = $\frac{Distance}{Time}$

So ,

Time taken = $\frac{Distance}{velocity}$
= $\frac{1500}{700}$

= 2.14285 seconds (approx.)

So ,
The time taken to cover a distance of 1.5 km or 1500 metres is 2.14285 seconds