Answer:
The expresion for the flux through the disk is:
Ф = E·πR^2·cos(Θ).
Explanation:
Let's sat the electric field has direction e and the normal to the disk has direction n (bold means vector quantities). So we have:
E=E·e (where E is the magnitud of the electric flied)
A=A·n
The flux for an uniform electric field and a flat surface is:
Ф=E×A
⇒ Ф = E·A·e×n = E·A·cos(angle(e,n)) = E·A·cos(Θ)
Since in this case the area is for a disk of radius R,
So, Ф = E·πR^2·cos(Θ)
Answer:
a. The sound will travel at the speed to both Jill and Jack
b. Jack
Explanation:
a. Doppler effect describes how the frequency of a sound wave changes with regards to an observer that has relative motion to the sound source;
The Doppler effect is given by the following formula;
For a sound that is moving away, as observed by Jill, we have;
For approaching sound, as observed by Jack, we have;
Where;
f = The sound wave's actual frequency
f' = The frequency of the moving sound to the observer
v = The speed of the sound wave
v₀ = The observer's velocity = 0
= The velocity of the source (the automobile honking) of the sound wave
From the above equation, we have that the speed of sound, 'v', is the same to both the source, and the observer although the frequency, and therefore, the wavelength of the sound alternatively increases or decreases
b. From the Doppler effect equation, the person who will hear the highest frequency is given by the formula for the frequency when the sound is approaching the observer, which has the lower denominator
Therefore, given that the automobile is travelling towards Jack, jack will hear the higher frequency