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March 29, 2024, 12:43:06 pm

Author Topic: VCE Physics Question Thread!  (Read 603434 times)  Share 

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Rod

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Re: VCE Physics Question Thread!
« Reply #645 on: October 08, 2014, 11:50:50 pm »
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Yes some older physics/specialist reports seemed to have this information, but I'm going based off the spreadsheet that my physics teacher gave me towards the end of last year which was his info on grade distributions and everything so idk he may have gotten the information from some other source related to being a VCE physics teacher. he had all sorts of info like that.
Hey silver sorry for the questions!

Would you reccomend me going through the qs for motion for 06? Or leave it?
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silverpixeli

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Re: VCE Physics Question Thread!
« Reply #646 on: October 09, 2014, 08:30:40 am »
+1
Where would you find the A+ cutoffs and things like that on the vcaa website for physics

go to VCAA website and search "grade distributions 2013" or whatever year you want, you should find a page with links to the distributions for each subject that year

Hey silver sorry for the questions!

Would you reccomend me going through the qs for motion for 06? Or leave it?

all the questions except 9* are still relevant, but it's an overall long section with some difficult ones. i think going through it with that mindset (that it's a source of challenging questions) could be beneficial! only if practice at harder questions is what you're after though.
it's all valid and in the course, it's just that motion exams usually don't contain so many difficult questions, there are normally only a few spread between a lot of more basic ones.

*question 9 is about reference frames, interesting physics but no longer in the course
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allstar

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Re: VCE Physics Question Thread!
« Reply #647 on: October 09, 2014, 11:18:41 am »
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thank you! silverpixeli

but at the top of the flight, wouldn't it still experience centripetal acceleration/therefore centripetal force downwards in that situation? in the same direction as its weight force? but its weight force is zero? unknow? im confused....

silverpixeli

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Re: VCE Physics Question Thread!
« Reply #648 on: October 09, 2014, 11:43:24 am »
+1
thank you! silverpixeli

but at the top of the flight, wouldn't it still experience centripetal acceleration/therefore centripetal force downwards in that situation? in the same direction as its weight force? but its weight force is zero? unknow? im confused....

its weight force is always mg and so never zero (like unless you have no gravity or no mass, so realistically a plane would always have weight)

at the top of the flight, it does experience centripetal motion and therefore there must be a centripetal force, which is the weight force in this situation (a centripetal force has to be a real force, it's not so much a type of force like friction or gravitational attraction as a label for a real force that causes circular motion. an actual force (gravity, friction, tension) is called centripetal if it causes circular motion)

because at the top of the curve the weight force is all that is needed to cause circular motion (weight force is acting as centripetal) there is no need for a normal reaction force on the wings, meaning Normal force = 0 (this is called apparent weightlessness)
« Last Edit: October 09, 2014, 11:46:23 am by silverpixeli »
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allstar

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Re: VCE Physics Question Thread!
« Reply #649 on: October 09, 2014, 10:01:50 pm »
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so for that question I would ans it like this?

the plane has a weight force because it has mass and experiences 9.8N (g) on the Earth.

weightlessness can never happen, cause for this to happen it requires g=0, which is like never? so it does not apply to any situation?

apparent weightlessness occurs bcause there is no normal reaction force acting on the plane because only the weight force is needed? but how do we know this?

silverpixeli

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Re: VCE Physics Question Thread!
« Reply #650 on: October 09, 2014, 11:10:23 pm »
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so for that question I would ans it like this?

the plane has a weight force because it has mass and experiences 9.8N (g) on the Earth.

weightlessness can never happen, cause for this to happen it requires g=0, which is like never? so it does not apply to any situation?

apparent weightlessness occurs bcause there is no normal reaction force acting on the plane because only the weight force is needed? but how do we know this?

yeah that's pretty much right, i just looked back at the question and noticed it wants answers directly about the passengers not the aircraft itself but it's all the same

  • the astronauts have a weight at all times, because of the gravitational field of the earth
  • weightlessness doesn't apply, the astronauts have weight, though they do 'feel' weightless at the top of the arc
  • this is apparent weightlessness, as there is no normal reaction force acting at this point (the only force acting is weight, which accounts fully for the plane's circular motion)

as for how we know only the weight force is needed, the diagram says 'zero-g' for the top of the arc. when we talk about something's 'g-force' we mean how much apparent weight they're feeling compared to actual weight. one-g is normal conditions, 1.8-g is feeling heavier than normal, and zero-g is feeling weightless which means Normal = 0
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myanacondadont

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Re: VCE Physics Question Thread!
« Reply #651 on: October 11, 2014, 09:53:36 am »
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Hi all, I was doing the 2008 VCAA exam 1. In the electronics and photonics section it shows a npn transistor and stuff like that. That's no longer in our course right? Just want to confirm. I don't even know how to go about the question.

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Re: VCE Physics Question Thread!
« Reply #652 on: October 11, 2014, 10:15:03 am »
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Hi all, I was doing the 2008 VCAA exam 1. In the electronics and photonics section it shows a npn transistor and stuff like that. That's no longer in our course right? Just want to confirm. I don't even know how to go about the question.

yeah transistors were taken out of the study design and circuits involving them are no longer examinable
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Brunette15

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Re: VCE Physics Question Thread!
« Reply #653 on: October 11, 2014, 03:32:11 pm »
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Can someone please help me with this question from the 2006 vcaa exam 2?
I am unsure how they found the change in time. I presume they converted the 4m/s using a distance but I can't interpret what the distance would be. :-[
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Re: VCE Physics Question Thread!
« Reply #654 on: October 11, 2014, 03:54:41 pm »
+1
Can someone please help me with this question from the 2006 vcaa exam 2?
I am unsure how they found the change in time. I presume they converted the 4m/s using a distance but I can't interpret what the distance would be. :-[

Hey Brunette
Speed=Distance/time
the speed they used is obviously 4cm/s but the distance is 2cm. They used the length of the loop.
so 2/4 = 0.5s

let me know if this makes sense or not
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Re: VCE Physics Question Thread!
« Reply #655 on: October 13, 2014, 06:09:37 pm »
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hey guys, another quick momentum question

when the slope of a momentum vs time graph is equal to 0, this shows that momentum in conserved right.

So for explaining this:

Do i say, because the slope of p vs t graph is force, if it is equal to 0, there is no net external force acting on the system and hence it is isolated and hence momentum is conserved??

Btw what i have is a graph of p vs t, with two points before collision and two after, the teacher said to put in two lines of best fit separately for before and after collsion and then compare them....
The slope values of both lines of best fit are very close to 0 but i am just having trouble explaining/comparing them to come to a conclusion that momentum is conserved.
 

myanacondadont

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Re: VCE Physics Question Thread!
« Reply #656 on: October 13, 2014, 07:21:08 pm »
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^ Sorry not sure how to help. Did like 1 prac all year with our teacher and even though he said we had to like 4 we never did. Odd huh?

Anyway; does anyone have any 2013/2014 practice exams they could spare? My teacher gave us a total of 6 commercial exams, and I've gone and completed all the VCAA ones (some of which I'm now onto doing twice) soooooo yeah. If anyone has any I'd greatly appreciate it

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Re: VCE Physics Question Thread!
« Reply #657 on: October 20, 2014, 08:10:20 pm »
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Hey guys, quick question
How do you know whether to use the formula net force=Fn+Fg, or net force=Fn-Fg?
Thanks!

myanacondadont

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Re: VCE Physics Question Thread!
« Reply #658 on: October 20, 2014, 08:33:58 pm »
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Have a look at my attachment Maurlock. I hope it is clear, if not I can help explain further.

edit: Should just add that we know it is Fn-Fg since net centripetal force is always directed to the center.
« Last Edit: October 20, 2014, 08:35:42 pm by myanacondadont »

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Re: VCE Physics Question Thread!
« Reply #659 on: October 20, 2014, 10:10:42 pm »
+4
Hey guys, quick question
How do you know whether to use the formula net force=Fn+Fg, or net force=Fn-Fg?
Thanks!

Don't remember formulas. Think about the direction of the net force and where the normal, weight forces are pointed.
For a car on top of the hill, the net force must be directed down towards the centre of the hill. It therefore makes sense to define down as positive (you can choose whatever direction you want to be positive). Therefore, the normal force, pushing up on the car, is going to be negative. You'll have net force = weight force - normal force as the normal force is opposing the net force
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