You set a tuning fork into vibration at a frequency of 723 Hz and then drop it off the roof of the Physics building where the acceleration due to gravity is 9.80 m/s2. Determine how far the tuning fork has fallen when waves of frequency 697 Hz reach the release point?

Respuesta :

Answer:

Explanation:

Given

Original Frequency [tex]f=723\ Hz[/tex]

apparent Frequency [tex]f'=697\ Hz[/tex]

There is change in frequency whenever source move relative to the observer.

From Doppler effect we can write as

[tex]f'=f\cdot \frac{v-v_o}{v+v_s}[/tex]

where  

[tex]f'=[/tex]apparent frequency  

v=velocity of sound in the given media

[tex]v_s=[/tex]velocity of source

[tex]v_0=[/tex]velocity of observer  

here [tex]v_0=0[/tex]

[tex]697=723\cdot (\frac{343-0}{343+v_s})[/tex]

[tex]v_s=(\frac{f}{f'}-1)v[/tex]

[tex]v_s=(\frac{723}{697}-1)\cdot 343[/tex]

[tex]v_s=12.79\approx 12.8\ m/s[/tex]

i.e.fork acquired a velocity of [tex]12.8 m/s[/tex]

distance traveled by fork is given by

[tex]v^2-u^2=2as[/tex]

where v=final velocity

u=initial velocity

a=acceleration

s=displacement

[tex]v_s^2-0=2\times 9.8\times s[/tex]

[tex]s=\frac{12.8^2}{2\times 9.8}[/tex]

[tex]s=8.35\ m[/tex]

                                       

This question involves the concepts of doppler's effect and the equations of motion.

The tuning fork has fallen by a height of "8.36 m".

From Doppler's Effect we have:

[tex]\frac{f_o}{f_s}=\frac{v+v_o}{v+v_s}[/tex]

where,

[tex]f_o[/tex] = apparent frequency of sound waves = 697 Hz

[tex]f_s[/tex] = actual frequency of sound waves = 723 Hz

v = speed of sound = 343 m/s

[tex]v_o[/tex] = speed of observer = 0 m/s

[tex]v_s[/tex] = speed of source = ?

Therefore,

[tex]\frac{697\ Hz}{723\ Hz}=\frac{343\ m/s + 0\ m/s}{343\ m/s+v_s}\\\\343\ m/s+v_s=\frac{343\ m/s}{0.964}\\\\v_s = 355.8\ m/s - 343\ m/s\\v_s = 12.8\ m/s[/tex]

Now, we will use the third equation of motion to find out the height fell by the tuning fork:

[tex]2gh=v_f^2-v_i^2[/tex]

where,

g = acceleration due to gravity = 9.8 m/s²

h = height fell = ?

vf = final speed of tuning fork = v_s = 12.8 m/s

vi = initial speed of tuning fork = 0 m/s

Therefore,

[tex]h=\frac{(12.8\ m/s)^2-(0\ m/s)^2}{2(9.8\ m/s^2)}\\\\[/tex]

h = 8.36 m

Learn more about equations of motion here:

brainly.com/question/20594939?referrer=searchResults

The attached picture shows the equations of motion.

Ver imagen hamzaahmeds