HSC Physics Question Thread

[Maraos]

Yep, you're 100% right; that's the perfect practical task to use! The Galvanometer clearly shows that the current changes directions, so you've produced AC current

Ah okay thanks for the clarification!

[gilliesb18]

Thanks Jamon, that definitely helps....
I've been working it out, but is there any way that you could upload a triangle diagram of it??? Is that asking waaay too much??
Thanks heaps....

[jamonwindeyer]

Thanks Jamon, that definitely helps....
I've been working it out, but is there any way that you could upload a triangle diagram of it??? Is that asking waaay too much??
Thanks heaps....

Definitely can do that!! I'll draw one up soon when I get a chance!

[itssona]

heeey for this  question (question 10), would we do mass (72) x 9.8 and that is weight force going down, so that means the force going up is also this?

what happens to the 2m/s though? I dont get how the 2 even gets involved argh

please answer within 3 hours since my exam is then aha, thank you guys

[jamonwindeyer]

heeey for this  question (question 10), would we do mass (72) x 9.8 and that is weight force going down, so that means the force going up is also this?

what happens to the 2m/s though? I dont get how the 2 even gets involved argh

please answer within 3 hours since my exam is then aha, thank you guys

Hey! You are right on the money - If we have a constant velocity that means no net force, so the force upwards needs to balance the force downwards (which is why we use an acceleration of 9. - The velocity actually doesn't come into the question! Velocity is constant - We only need to apply enough force to balance the weight force, the velocity is a red herring

[itssona]

Hey! You are right on the money - If we have a constant velocity that means no net force, so the force upwards needs to balance the force downwards (which is why we use an acceleration of 9. - The velocity actually doesn't come into the question! Velocity is constant - We only need to apply enough force to balance the weight force, the velocity is a red herring

ahhh thank you Jamon! Ugh I'll have to make it a point to be cautious of such red herrings! XD

[Rathin]

Help with ii) please

[jamonwindeyer]

Thanks Jamon, that definitely helps....
I've been working it out, but is there any way that you could upload a triangle diagram of it??? Is that asking waaay too much??
Thanks heaps....

[jamonwindeyer]

Help with ii) please

Sure! So we know that the induced emf is:



Now \(\Phi=BA\), so the change in emf is completely dependent on change in area (since time and field strength are not changing). But area is given by \(A=\pi r^2\), so, if the radius is decreasing, you don't have a constant rate of decrease in area. Now, the rate of change in area is actually linear.

You know Calculus, so we can actually (optionally) consider it this way:



So, the area decreases more slowly as \(r\) decreases. You start with a higher induced EMF, then linearly decrease to a lower value (immediately dropping to zero after the time has elapsed) this is a tough one, does it make sense?

[Bubbly_bluey]

Hello! Just curious but why does the fluorescence emitted by cathode rays green?

[jakesilove]

Hello! Just curious but why does the fluorescence emitted by cathode rays green?

No particular reason here; the film itself would be designed such that, when the lattice is excited (ie. by having electrons hit it), it glows green! It could probably be set up to glow blue if you wanted to.

[gilliesb18]

Thanks heaps for that!!!

[Sukakadonkadonk]

Hey Guys,

Does anyone know what the difference is between 1 rayl and 1 kg m^-2 s^-1
in terms of acoustic impedance? Can they be used interchangeably?

or is 1 rayl just equal to 10^6 1 kg m^-2 s^-1

Thanks.

[Aaron12038488]

is nanometers x 10-6, whats 10*-9?

[cxmplete]

Hi,
Does anyone know how to write a 6 mark response for this hsc question, because I'm pretty stuck rn?
(and no I don't have the success one book)