Question

According to the Doppler effect, if a car with a blowing horn is moving toward you, the pitch you hear will

Answer 1

Answer:

If a car with a blowing horn is moving toward you, the pitch sounds higher than the actual emitted frequency.

Step-by-step explanation:

In figure,

        V= speed of wave

         U= speed of car

When car moving towards you, then

Car travels a distance in time T = VT

 Wave travels a distance in time T = UT

From figure,

                    change in wavelength (λ') = VT - UT= T(V-U)

Now,

        V = λ' f'         (f' →frequency observed by you)

         f' = V ÷ λ' = $\frac{V}{T(V-U)}$

We know that

                      $\frac{1}{T}$ = f

Then,

        f' =  $\frac{Vf}{V-U}$

        f' = $\frac{f}{1-\frac{U}{V} }$

Hence, we can say that

           frequency increases as source moves toward you.

Answer 2

Answer:

B. Increase

Step-by-step explanation:

The closer together the crests, the higher the frequency (or pitch)