VCE Physics Question Thread!

[Swagadaktal]

Hey guys
Does sound change air density?
Like with compressions and rarefactions does the air density change at those points?

[jyce]

Hey guys
Does sound change air density?
Like with compressions and rarefactions does the air density change at those points?

Yep, compressions of sound = areas of high air pressure, rarefactions = areas of low air pressure.

[Swagadaktal]

Yep, compressions of sound = areas of high air pressure, rarefactions = areas of low air pressure.

wew thank God omg u make me so happy jyce <3

[@#035;3]

Can someone pls show me how to do VCAA 2006 EXAM 2 Q6 structures and materials.
Cheers.

[Syndicate]

Can someone pls show me how to do VCAA 2006 EXAM 2 Q6 structures and materials.
Cheers.

What page number is it on the exam?

[@#035;3]

ah shit I meant to write VCAA 2004 EXAM 2 STRUCTURES AND MATERIALS.. Sorry about that..
here's the link: http://www.vcaa.vic.edu.au/Documents/exams/physics/physics22004.pdf it's on page18 CHEERS
EDIT: DW figured it out

[CarrymetoUni]

If all three resistors have the same value, what is the ratio Vout/Vin? 
I'm unsure about this question, please help me out. Is the ratio 1/2 since 2 resistors are in parallel and one is in series. I have attached a picture of the circuit.

[Swagadaktal]

If all three resistors have the same value, what is the ratio Vout/Vin? 
I'm unsure about this question, please help me out. Is the ratio 1/2 since 2 resistors are in parallel and one is in series. I have attached a picture of the circuit.

if u have 2 resistances in parallel of same resistance, then the effective resistance halves.
So  the Voltage dissipated of the parallel will be half the voltage on the single R.
Therefore the ratio it 2:1

[CarrymetoUni]

Thanks for answering my question...I have another one 
An LED and a light dependent resistor (LDR) are being used in the circuit shown below to transmit data from a computer to a printer.  The circuits are as shown below.  The control block (data) adds the zero referenced data signal (one that varies plus and minus around zero) to the DC 10V supply.  The control block has a max, peak to peak output of 20V (I.e. from -10V to +10V)

What will the minimum and maximum voltages at A be?

[bedigursimran]

Hi guys, I have a materials and structures question (and answer) that I have attached below. Hope you guys can have a look at and help me.
 I don't understand why the answers are figuring out the length y to find torque and thus tension in cable. I may be missing something in my understanding. Thanks so much!

[StupidProdigy]

Hi guys, I have a materials and structures question (and answer) that I have attached below. Hope you guys can have a look at and help me.
 I don't understand why the answers are figuring out the length y to find torque and thus tension in cable. I may be missing something in my understanding. Thanks so much!

torque=f*d (note that d must be the perpendicular distance to the force! 'y' is the perpendicular distance from point O to the tension force). Alternatively, to do this question without finding the distance 'y', you can resolve the tension force in horizontal and vertical components and find the torques which these components create (the horizontal component will create zero torque as the force's line of action will pass through point O). Finally, they have chosen point O to take the torque about since there is a reaction force here, but it becomes neglected in the analysis since it passes through point O. Did that help?

[HopefulLawStudent]

There are two conductors, m and n that are placed next to each other a distance of 2R apart from one another on the east-west axis. If m carries a current into the page and n carries a current out of the page, at which of the following points could a third conductor experience zero magnetic force?

A. a point between m and n
B. a point west of m
C. a point east of n

Also attempted a diagram of what they're saying (please excuse the dodginess of my drawing tho   )

Please. Someone help.

[wyzard]

Also attempted a diagram of what they're saying (please excuse the dodginess of my drawing tho   )

Please. Someone help.

The answer's A, as the magnetic field from both wires cancel each other out in the middle.Just trace out the magnetic field produced by each wire using the right-hand grip rule and you'll see why.

[HopefulLawStudent]

Nope. The answer's B and C, apparently. I thought the answer would be A too but it's not and I don't get why.

[wyzard]

Nope. The answer's B and C, apparently. I thought the answer would be A too but it's not and I don't get why.

Oh wait a minute, made a silly mistake earlier as I was in a hurry.

The magnetic fields in the middle are pointing in the same direction. Along the west and east of conductor m and n, the magnetic fields cancel out partially, however it will never be zero. It does however approach to zero as you get further and further away, so I think that is what the question meant.

On a side note, you can actually make A the correct answer by orientating the third wire perpendicular m and n, making it parallel to the field produced.