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Physics Multiple Choice Question

Can someone please explain what the answer to this question will be and why?
Attachment not found

https://imgur.com/fUsY9GG
(edited 6 years ago)
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JackF89
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Original post by cotton candie
Can someone please explain what the answer to this question be and why?

Attachment not found


what's the question? If you post it I might be able to help
Original post by JackF89
what's the question? If you post it I might be able to help

Here's the link.Thanks!

https://imgur.com/fUsY9GG
(edited 6 years ago)
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have
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Original post by cotton candie
Its in the attachment.Thanks!


attachment not found.
don't trust tsr's *****y image upload. upload it to imgur or wherever and post the link
Original post by StayWoke
attachment not found.
don't trust tsr's *****y image upload. upload it to imgur or wherever and post the link


Oh! Can u still not see it????
Original post by StayWoke
attachment not found.
don't trust tsr's *****y image upload. upload it to imgur or wherever and post the link


Here: https://imgur.com/fUsY9GG
Reply 6
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have
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Original post by cotton candie


Before they hit the car, wavelength = c/f
Let t=0 be a time when a maximum has just hit the car, what will t be when the next maximum hits the car.
The next maximum will obviously be c/f behind the car
Distance travelled by car = distance travelled by wave - 1 wavelength (since it starts one wavelength behind)
vt = ct - c/f
solve for t
t = (c/f)/(c-v) = c/ f(c-v)
The distance the car has travelled in this time = cv / f(c-v)

Cool, we have the info we need.
This second maximum has just hit the car, where is the first maximum?
The first maximum hit the car cv/f(c-v) closer to the gun than the second maximum, but then on top of that it also travelled for c/f(c-v) seconds back towards the radar gun.
It's new distance from the second maxmimum = cv/f(c-v) + c^2/f(c-v).
= c(c+v)/f(c-v)
This is the new wavelength.
Frequency = speed/ wavelength
= c * f(c-v) / c(c+v)
=f(c-v)/(c+v).

That's what I got, but it isn't an option :/

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