Can you please explain this to me?- GCSE Physics

I have lookbin the morning what secyion is p1 p2 p3

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I'm sorry as I don't know the answer, but the fact that I will be sitting my P1 exam in June is made a lot more scary after looking at that question! I haven't even started core physics revision as I have been doing additional and triple doed the mark scheme not explain it?

I really do not understand question 8) b)ii

Can someone explain the answer for the question for me?
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Here is the paper

http://filestore.aqa.org.uk/subjects/AQA-PH1HP-QP-JUN13.PDF

I really do not understand question 8) b)ii

Can someone explain the answer for the question for me?
`
Here is the paper

http://filestore.aqa.org.uk/subjects/AQA-PH1HP-QP-JUN13.PDF

Well first of all, without having to understand anything about the question you can work it out just with common sense.

It's not the first answer because you can't prove a theory that's about the past, same with evolution aswell. You can only gather evidence that supports it.

So it can only be the 2nd or 3rd answer.

Well it can't be the 3rd answer because (same reason as the first and also) theres not enough known about the universe to make a statement like that about the future.

So it can only be the 2nd answer.


But ye the question is about redshift. Basically everything is moving away from the center of the universe, including waves from the electromagnetic spectrum (light), and because we're moving further away it stretches the wave so that it moves to the 'red' side of the electromagnetic spectrum.

Its the same with sound waves when a car drives past you. When a formula 1 car is moving towards you it will sound very high pitched because the waves get compressed. But when it drives passed you it sounds lower pitched because the waves are getting stretched by the car moving away. (think of it like a slinky attatched to the car, but the slinky is trying to get towards you in both instances ).

So in the case of the universe, earth is moving away from the center of the universe. And we can say that because of the stretched microwaves. If we were moving towards the center of the universe it would be blue shift and we'd be detecting gamma rays instead (or stuff on that side of the spectrum).


edit: lol my bad I was looking at 8a)ii) , the question is still about blue and red shift anyway though.

Basically, you know when something is moving away from you it redshifts, and if it is moving closer it blueshifts? In the spectral diagrams in comparison to the sun one is moving away and is redshifted (star A) and the other is moving closer (star B). If star B was orbiting star A and A wasn't orbiting B, then at that point in time star A would not be moving, so would have the same lines as the sun. As both are moving it can be assumed that they are orbiting each other.

Sorry if I haven't explained it correctly, if you still don't understand I will try and explain it a bit better.

Ah, I remember doing this in a mock and found it a bit weird at first.

As one is redshifted (moving away you) and one is blueshifted (moving towards you), they must be orbiting round a central point and on different sides otherwise they would both be moving the same way. Try drawing a diagram to clear up your thinking.

Posted from TSR Mobile

I really do not understand question 8) b)ii

Can someone explain the answer for the question for me?
`
Here is the paper

http://filestore.aqa.org.uk/subjects/AQA-PH1HP-QP-JUN13.PDF

Hello, here is the ans. hope it helps. best wishes...

A comparison of the spectra from the two stars in a binary star system provides evidence to support this conclusion as the given position in time shown by the observed spectrum from star A
shows that star A is moving further away from the Earth. On the other hand, light emitted from star B shows a decrease in the wavelength, which suggests that star B is moving towards the Earth.