General Thoughts: Physics (1 Viewer)

[machine2035]

ah fuck man, I didn't do calculations, and I just explained it

I started like that when I realised the question specifically mentioned calculations.. I went below "End of question" on the page so the marker probs be mad.

 

[nirukk]

Yeah... i got 29.86ms i dont know why the projectile was worth so much.

I got the same. I used v^2 = u^2 +2as
and then use pythagoras.

 

[harudew]

Anyone got any thoughts on that tower question. Where we supposed to take it as an inertial frame or referance? If not what the fwark.

 

[lance687876]

Anyone got any thoughts on that tower question. Where we supposed to take it as an inertial frame or referance? If not what the fwark.

LOL where did that come from?

 

[oh well]

Anyone got any thoughts on that tower question. Where we supposed to take it as an inertial frame or referance? If not what the fwark.

you high brah?

 

[Zeroes]

Anyone got any thoughts on that tower question. Where we supposed to take it as an inertial frame or referance? If not what the fwark.

I talked about how they would both appear to fall straight down from an observer on the earth's frame of reference like hit ground at same time, same acceleration etc (edit: assuming g = 9.8) but from a frame of reference external to the earth but stationary with respect to tower A, B would appear to fall with a parabolic trajectory due to the earth's rotational velocity.
My teacher agreed so I think that's right...

 

[luke0410]

I talked about how they would both appear to fall straight down from an observer on the earth's frame of reference like hit ground at same time, same acceleration etc but from a frame of reference external to the earth but stationary with respect to tower A, B would appear to fall with a parabolic trajectory due to the earth's rotational velocity.
My teacher agreed so I think that's right...

i wrote about the exact same thing, but according to everyone elses answer
i wanna cry lol

 

[luke0410]

and the "thought experiment" in the title made me lean towards simultaneity woops

 

[oh well]

and the "thought experiment" in the title made me lean towards simultaneity woops

huh

 

[lance687876]

I talked about how they would both appear to fall straight down from an observer on the earth's frame of reference like hit ground at same time, same acceleration etc but from a frame of reference external to the earth but stationary with respect to tower A, B would appear to fall with a parabolic trajectory due to the earth's rotational velocity.
My teacher agreed so I think that's right...

l think your teacher's just tryna cheer you up lol

 

[Zeroes]

I didn't know what to write for Q.34, c)

Like I didn't know how to relate that neutron shit to De Broglie's work :S

Was that the neutron one? You talk about how de Broglie's hypothesis about particles exhibiting wave-like properties and having a wave length, and because of that neutrons can be diffracted, analyse diffraction patterns etc.

 

[Zeroes]

l think your teacher's just tryna cheer you up lol

Someone else asked her, I hadn't even told her my answer.
So no.

Edit: Oh, I see what you mean, you interpreted it as a question about the difference in the value of g. You probably needed to mention frames of references as well, you won't get 3 marks just for saying the earth isn't perfectly round.

 

[luke0410]

huh

can you read

 

[Heydosaurus]

Was that the neutron one? You talk about how de Broglie's hypothesis about particles exhibiting wave-like properties and having a wave length, and because of that neutrons can be diffracted, analyse diffraction patterns etc.

I looked at this and was like "DAFUCK DID I MISS A QUESTION?!"

Then I realised, option that I didn't do. Pheww. Actually, on the options, I really wish that we did Age of Silicon in class. Those questions looked awesome. Right up my alley, and it would have been complimentary with Engineering Studies, and to an extent, IPT.

 

[oh well]

can you read

Nah <.>

 

[LlamaBoi]

Really fair exam imo but 2 things...

Best would be B because A was high current (max power lost) and C was way too fkin expensive

It didn't ask about price, so C was actually the best choice because of its efficiency
and also for that length contraction one it was 40.2 cm because it was asking from the electron's point of reference. I came across a question very similar to this one where you had to really think about your reference points
But otherwise I pretty much agree with everything else

 

[DrWho94]

urgh if it was from the electrons frame of reference, then there would be no change since the laws of physics hold true in an inertial frame of reference. (remain 40cm)

I Thought this too but I remember reading that for length contraction space appear to contract not necessarily just the vehicle or in this case the particle. So I went with that.

 

[RishBonjour]

Really fair exam imo but 2 things...



It didn't ask about price, so C was actually the best choice because of its efficiency
and also for that length contraction one it was 40.2 cm because it was asking from the electron's point of reference. I came across a question very similar to this one where you had to really think about your reference points
But otherwise I pretty much agree with everything else

electrons frame of reference will be short since its travelling at relativistic speed. from its point of view, the cathode is movign towards it at relativistic speed - hence its 39.something cm. The one you are talking about was the other way around.

 

[brianphamm]

^But you need to use more power for cooling in C than you would lose in B, right?
(My calculations were fucked so I'm not 100% sure on this)

+1

electrons frame of reference will be short since its travelling at relativistic speed. from its point of view, the cathode is movign towards it at relativistic speed - hence its 39.something cm. The one you are talking about was the other way around.

+1

 

[LlamaBoi]

electrons frame of reference will be short since its travelling at relativistic speed. from its point of view, the cathode is movign towards it at relativistic speed - hence its 39.something cm. The one you are talking about was the other way around.

That was the whole point, you have to imagine that the particle is stationary and the anode is moving towards it, not the other way around. So if it asked from an observers perspective then it would contract but from the electrons perspective it would increase.
Bad example but if youve ever seen star trek or something and as soon as they start travelling at light speed (which is impossible but whatever) all of the stars stretch out around them, because everything around them gets longer.