Respuesta :
Answer:
a) [tex]T=1.43\times 10^{-3}\ s[/tex]
b) [tex]d=0.0429\ m[/tex]
c) [tex]\lambda=0.4857\ m[/tex]
d) [tex]f_o=767.7\ Hz[/tex]
Explanation:
Given:
- velocity of the sound from the source, [tex]S=340\ m.s^{-1}[/tex]
- original frequency of sound from the source, [tex]f_s=700\ Hz[/tex]
- speed of the source, [tex]v_s=30\ m.s^{-1}[/tex]
(a)
We know time period is inverse of frequency:
Mathematically:
[tex]T=\frac{1}{f}[/tex]
[tex]T=\frac{1}{700}[/tex]
[tex]T=1.43\times 10^{-3}\ s[/tex]
(b)
Distance travelled by the motorcycle during one period of sound oscillation:
[tex]d=v_s.T[/tex]
[tex]d=30\times 1.43\times 10^{-3}[/tex]
[tex]d=0.0429\ m[/tex]
(c)
The distance travelled by the sound during the period of one oscillation is its wavelength.
[tex]\lambda=\frac{S}{f}[/tex]
[tex]\lambda=\frac{340}{700}[/tex]
[tex]\lambda=0.4857\ m[/tex]
(d)
observer frequency with respect to a stationary observer:
According to the Doppler's effect:
[tex]\frac{f_o}{f_s}= \frac{S+v_o}{S-v_s}[/tex] ...........................(1)
where:
[tex]f_o\ \&\ v_o[/tex] are the observed frequency and the velocity of observer respectively.
Here, observer is stationary.
[tex]\therefore v_o=0\ m.s^{-1}[/tex]
Now, putting values in eq. (1)
[tex]\frac{f_o}{700}= \frac{340+0}{340-30}[/tex]
[tex]f_o=767.7\ Hz[/tex]
