Login

Welcome, Guest. Please login or register.

March 29, 2024, 02:09:47 am

Author Topic: VCE Physics Question Thread!  (Read 603255 times)  Share 

0 Members and 3 Guests are viewing this topic.

Evolio

  • MOTM: MAY 20
  • Forum Leader
  • ****
  • Posts: 604
  • Respect: +485
Re: VCE Physics Question Thread!
« Reply #2355 on: January 29, 2020, 07:29:38 pm »
+6
Hey everyone,

How does significant figures work, like how many sig figs are there in 13.07 and 13.0 and 13 and 2.00, 2.0, 3.03 x10^8

Thanks in advance😀😀
Hey SmartWorker!

13.07: 4 sig figs
13.0: 3 sig figs
13: 2 sig figs
2.00: 3 sig figs
2.0: 2 sig figs
3.03x10^8: 3 sig figs.

Rules:
- Following zeros (after non-zero numbers) are always significant
- Leading zeros (before non-zero numbers) are never significant
- Zeros in between non-zero numbers count as a sig fig
- All numbers except 0 count as a sig fig
This is specified by VCAA here: https://www.vcaa.vic.edu.au/curriculum/vce/vce-study-designs/Physics/advice-for-teachers/Pages/MeasurementinScienceQuantitativeAnalysisofUncertainty.aspx

Please correct me if I'm wrong!
« Last Edit: January 29, 2020, 07:57:16 pm by Evolio »

milanander

  • Trendsetter
  • **
  • Posts: 114
  • Nehemiah 8:10
  • Respect: +85
Re: VCE Physics Question Thread!
« Reply #2356 on: January 29, 2020, 08:37:40 pm »
0
I'll be completely honest here. I went through Mathematics Ext 2, hardcore University Maths like Complex Analysis and Vector Calculus and I still don't know how they work. I just let my calculator do sig figs for me lol

What type of calculator figured out sig figs for you?
— 2019 • 2020 —
UMEP 4.0, Systems 41, Methods 47, Specialist 46, Physics 46, Viscom 40, English 37
ATAR 99.20

— 2021 • 2023 —
Bachelor of Design (Mechanical Systems & Graphic Design)
University of Melbourne

DrDusk

  • NSW MVP - 2019
  • Forum Leader
  • ****
  • Posts: 504
  • Respect: +130
Re: VCE Physics Question Thread!
« Reply #2357 on: January 29, 2020, 08:53:22 pm »
+3
What type of calculator figured out sig figs for you?
Casio fx-100 AU PLUS. It's a standard calculator that most people use in NSW.

Erutepa

  • VIC MVP - 2019
  • Forum Leader
  • ****
  • Posts: 721
  • evenin'
  • Respect: +775
Re: VCE Physics Question Thread!
« Reply #2358 on: January 30, 2020, 09:44:48 pm »
+5
Hi, I was wondering if I could have some help with this physics motion question. Thanks! ;D

As a result of being hit from behind by a toy truck, a 250 g toy car, initially at rest rolls 10 m across a floor that applies a constant retarding force of 0.75N to it. The car stops 6 seconds after being hit.

a)If the truck was in contact with the car for 0.12 seconds, calculate the impulse given to the car.
b) Calculate the momentum of the car just after being hit.
c) Calculate the instantaneous speed of the car just after being hit.
d) Calculate the average force applied to the car during the collision.
Hey BitcoinEagle
myself and others are more than happy to answer your question, but before we do its important for you to have a go at it first and try to explain your current aproach to the question. Are you having difficulty with all of these parts (a,b,c,d) or is there one particular part that you are not understanding?

Having a go at the question first and showing us your thinking process helps people answering your question figure out what specifically you don't quite get so that we can better help you towards understanding the question. And don't worry about being wrong as every mistake is an opportunity to learn and improve!

That being said, it might be good to start with the formula:


where 'I' here is the impulse
« Last Edit: January 30, 2020, 09:51:17 pm by Erutepa »
Qualifications
 > Have counted to 227
 > Can draw really good spiders
 > 2 Poet points
 > 6.5 insanipi points
 > 1 Bri MT point

Gogurt

  • Adventurer
  • *
  • Posts: 8
  • Respect: 0
Re: VCE Physics Question Thread!
« Reply #2359 on: February 20, 2020, 08:23:46 pm »
0
Can anyone explain why the answer is A? I've spent a good amount of time on this, and I haven't got a clue. I'm mostly confused on why the friction force is facing the same direction that the car is accelerating in.

DrDusk

  • NSW MVP - 2019
  • Forum Leader
  • ****
  • Posts: 504
  • Respect: +130
Re: VCE Physics Question Thread!
« Reply #2360 on: February 20, 2020, 09:22:43 pm »
+7
Can anyone explain why the answer is A? I've spent a good amount of time on this, and I haven't got a clue. I'm mostly confused on why the friction force is facing the same direction that the car is accelerating in.
Think about it this way. Suppose a car is moving to the right. This means its tires are rotating clockwise. The bottom of the tire therefore exerts a force to the left on the road in order for the car to go forward. Friction needs to oppose this motion force which means it will point to the right.

When you think about these kind of questions conceptually you must think about exactly what the force is acting on or else you will get confused. This is because the car is moving to the right but the tires are actually rotating in the 'opposite' direction of the cars acceleration so to speak. So isolate the component that the force is actually acting on and think about it that way instead of just the whole car itself. Friction is NOT acting on the car but rather the tires and the tires follow a separate motion to the car in a sense..
« Last Edit: February 20, 2020, 09:27:40 pm by DrDusk »

Erutepa

  • VIC MVP - 2019
  • Forum Leader
  • ****
  • Posts: 721
  • evenin'
  • Respect: +775
Re: VCE Physics Question Thread!
« Reply #2361 on: February 20, 2020, 09:39:59 pm »
+7
Can anyone explain why the answer is A? I've spent a good amount of time on this, and I haven't got a clue. I'm mostly confused on why the friction force is facing the same direction that the car is accelerating in.
Welcome to the forums Gogurt!
In addition to what Dr Dusk has said above,

In diagram A, the wheel rotates clockwise and applie a force on the ground acting to the left, consequentially the ground applied an equal and opposite frictional force acting towards the right. This causes the car to accelerate.
In diagram B, think of the wheel is slowing down/stopped as it applies a force on the ground acting to the right (this is essentially the same as imagining a stationary wheel staring to reverse - as it rotates anticlockwise, it will apply a force on the ground acting to the right. As a result, an equal and opposite frictional force will be exerted by the ground on the wheel in the left direction.
This kinda explains why the force is acting as it is, but the best way to get to the answer is by simply considering the directions of motion and the directions of the force. In diagram A, the frictional force acts in the direction of motion, causing the car to accelerate to the right, while in diagram B, the frictional force acts opposite to the direction of motion, causing the car to deccelerate.

Hopefully this helps, but feel free to point out anything you still don't unserstand/anything I may not have explained clearly. :)
« Last Edit: February 20, 2020, 09:42:05 pm by Erutepa »
Qualifications
 > Have counted to 227
 > Can draw really good spiders
 > 2 Poet points
 > 6.5 insanipi points
 > 1 Bri MT point

Gogurt

  • Adventurer
  • *
  • Posts: 8
  • Respect: 0
Re: VCE Physics Question Thread!
« Reply #2362 on: February 23, 2020, 09:56:05 am »
0
Think about it this way. Suppose a car is moving to the right. This means its tires are rotating clockwise. The bottom of the tire therefore exerts a force to the left on the road in order for the car to go forward. Friction needs to oppose this motion force which means it will point to the right.

When you think about these kind of questions conceptually you must think about exactly what the force is acting on or else you will get confused. This is because the car is moving to the right but the tires are actually rotating in the 'opposite' direction of the cars acceleration so to speak. So isolate the component that the force is actually acting on and think about it that way instead of just the whole car itself. Friction is NOT acting on the car but rather the tires and the tires follow a separate motion to the car in a sense..

In diagram A, the wheel rotates clockwise and applied a force on the ground acting to the left, consequentially the ground applied an equal and opposite frictional force acting towards the right. This causes the car to accelerate.
In diagram B, think of the wheel is slowing down/stopped as it applies a force on the ground acting to the right (this is essentially the same as imagining a stationary wheel staring to reverse - as it rotates anticlockwise, it will apply a force on the ground acting to the right. As a result, an equal and opposite frictional force will be exerted by the ground on the wheel in the left direction.
This kinda explains why the force is acting as it is, but the best way to get to the answer is by simply considering the directions of motion and the directions of the force. In diagram A, the frictional force acts in the direction of motion, causing the car to accelerate to the right, while in diagram B, the frictional force acts opposite to the direction of motion, causing the car to deccelerate.

Hopefully this helps, but feel free to point out anything you still don't unserstand/anything I may not have explained clearly. :)

Ah that makes so much sense, thanks a lot!

TheEagle

  • Forum Obsessive
  • ***
  • Posts: 361
  • Respect: +12
Re: VCE Physics Question Thread!
« Reply #2363 on: May 03, 2020, 07:16:01 pm »
0
Why is the normal force considered as your apparent weight?
It says, "when the elevator is accelerating upwards, you feel heavier due to a larger normal force, however, I thought you will feel lighter due to gravity being less, thus less drag downwards compared to the normal force.

ashmi

  • MOTM: June 20
  • Moderator
  • Forum Obsessive
  • *****
  • Posts: 429
  • Living an illusion
  • Respect: +660
Re: VCE Physics Question Thread!
« Reply #2364 on: May 03, 2020, 07:33:30 pm »
+9
Why is the normal force considered as your apparent weight?
It says, "when the elevator is accelerating upwards, you feel heavier due to a larger normal force, however, I thought you will feel lighter due to gravity being less, thus less drag downwards compared to the normal force.
Hey TheEagle! ;D

If you think about it realistically on Earth, your weight (mg) won't change regardless of what is happening to you, however, your Normal force can change to reflect net forces. Let's say someone was 70kg and in an elevator. Their weight would be 868 Newtons ( 70* 9.8 ) and that will never change so long as they stay within the surface of Earth.

Now let's take that scenario of an elevator accelerating upwards (Fnet is up). Your weight (mg) is always constant and will never change, and due to Newton's Second Law, F = ma, for you to be accelerating upwards, your normal force will actually increase to reflect this scenario. I've drawn a diagram below to help explain this visually. Notice how the arrow length of the Normal force changes? This is to account for the situation someone in an accelerating/decelerating frame. Your acceleration on Earth is always 9.8ms^-2 DOWN no matter where you are (so long as you don't go past the surface), your mass doesn't change and as such your weight doesn't change either.
When the normal force is less than mg, you feel lighter and when it is bigger than mg, you feel heavier. You FEEL the effect of the force. Hope that helps!

« Last Edit: May 03, 2020, 07:35:38 pm by ashmi »

thisissara

  • Adventurer
  • *
  • Posts: 9
  • Respect: 0
Re: VCE Physics Question Thread!
« Reply #2365 on: June 02, 2020, 01:37:28 pm »
0
Hey guys,

I was just wondering is there ever a time where you do use Fleming's left-hand rule in VCE physics? I've always thought that the left-hand rule was used for motors and the right-hand rule for generators? Could someone clarify this for me? if I am wrong could you also explain why? cheers!  ;D

Ryanyeltrom

  • Adventurer
  • *
  • Posts: 6
  • Respect: 0
Re: VCE Physics Question Thread!
« Reply #2366 on: July 26, 2020, 08:55:37 am »
0
Okay so my physics teacher at my school is new (previously retired) and he pretty much has no idea how to teach my class, even though we're an extremely small class. I'm not complaining or anything because I can't really do much about it, but I was wondering if anybody would be able to help me with tips for studying physics?

I feel like I always spend so long writing out notes and stuff on the topics, but then when it comes to using the formulas and applying concepts I just can't remember how to do it or how to use the equations. My teacher isn't helping the stress levels when it comes to this subject as he has been piling on SAC's and has jumped around from topic to topic without any real demonstrations on how to do what it's asking of us.

I don't want to fail physics or get a really bad mark for the exam all because my teacher wasn't sufficient with his teaching methods or resources he has supplied us with. And I'm struggling to figure out how to get into a good study routine for physics, because it's not a subject that comes very naturally or easily for myself.

Any replies or help will be greatly appreciated, and I know this is a bit late in the year but I'm just dumb and didn't realise how little I've comprehended so far.
Thanks.

Owlbird83

  • BLAA 2020
  • Victorian Moderator
  • Forum Leader
  • *****
  • Posts: 553
  • Respect: +785
Re: VCE Physics Question Thread!
« Reply #2367 on: July 26, 2020, 10:18:10 am »
+3
Okay so my physics teacher at my school is new (previously retired) and he pretty much has no idea how to teach my class, even though we're an extremely small class. I'm not complaining or anything because I can't really do much about it, but I was wondering if anybody would be able to help me with tips for studying physics?

I feel like I always spend so long writing out notes and stuff on the topics, but then when it comes to using the formulas and applying concepts I just can't remember how to do it or how to use the equations. My teacher isn't helping the stress levels when it comes to this subject as he has been piling on SAC's and has jumped around from topic to topic without any real demonstrations on how to do what it's asking of us.

I don't want to fail physics or get a really bad mark for the exam all because my teacher wasn't sufficient with his teaching methods or resources he has supplied us with. And I'm struggling to figure out how to get into a good study routine for physics, because it's not a subject that comes very naturally or easily for myself.

Any replies or help will be greatly appreciated, and I know this is a bit late in the year but I'm just dumb and didn't realise how little I've comprehended so far.
Thanks.

Hey, personally I think for physics, think that spending a lot of time writing notes isn't the most helpful, and you would be better to make a cheat sheet and spend that time practice questions. I know it might seem daunting to do exam questions if you don't feel confident on understanding the content but, it will get easier and you'll start to understand it better, (I had a topic that finally 'clicked' for me while I was doing the sac haha). I know it may seem oversimplified to say 'do' the questions if you don't know where to start, but you want to sort of wing the questions until they start to seem familiar. Have you made a cheat sheet?
-I recomend scanning your notes for all the formulas and writing them down concisely and try to avoid excess info, (you can add the units, and the meaning of each of the letters/symbols too)
(here's an example of how I set out part of my cheat sheet)
Spoiler
-Then when you get a question, identify the pieces of info they give you in the question (eg they give you current, length of wire, number of loops, magnetic field, and want you to find force)
-Then scan your cheat sheet for a formula with each of the pieces of info (eg, look through them all until you see F=nIlB)
- Check to see if they are in the correct units as they should be imputted into the formula, then sub the numbers in (rearrange if necessary), then type it exactly into your calculator.
-Remember to add units

Sorry if what I've written is something that's obvious, but I completely believe that for majority of the questions with formulas it's not necessary to understand what's going on to be able to do them. I relied heaps on my cheat sheet all the time.

For the questions that relate to understanding, it might be a good idea to familiarise yourself with the common ones that come up. Most of the worded questions that get you to explain things have been asked in slightly different ways throughout the years on past exams. If you practice them you'll start to feel more confident in knowing the certain points they want you to make each time. For example a common one is Len's law where you have to explain which way the current flows and why.
Spoiler
-flux will be increasing in coil towards right
-to oppose this, a flux is created in coil towards left
-therefore the induced current is upwards in the wire
(basically always these three points, but change the directions depending on question)
I've forgotten what others come up a lot, but if you start to notice them in past exams, check the answers in the vcaa exam reports for the key points they like you to make for those types of questions. (Also when I say do past exams, only do them when you've finished the content, I don't mean do full ones right now, if you've got checkpoints or textbook questions or questions from your teacher they are good ways to practice specific areas).

Since you've mentioned it being confusing with the jumping around different topics, maybe when you are studying, only focus on one AOS at a time until you get confident with it. Physics has super separate areas, so you want to be able to identify what areas the questions are from.

In summary, making cheat sheet and doing past questions is going to be the most helpful.
Don't worry if you don't understand everything right now, you aren't alone, (I never fully understood the last area of study, and blindly subbed the numbers into the formulas and it worked well for me).
Hope this helps, good luck :)
« Last Edit: July 26, 2020, 10:24:02 am by Owlbird83 »
2018: Biology
2019: Chemistry, Physics, Math Methods, English, Japanese
2020: Bachelor of Psychology (Monash)

a weaponized ikea chair

  • Trendsetter
  • **
  • Posts: 182
  • Respect: +12
Re: VCE Physics Question Thread!
« Reply #2368 on: August 24, 2020, 09:31:25 pm »
0
Hello,

I am not doing VCE, but am struggling to understand the mathematical formula for average velocity. Is it the change in displacement over the change in time, or is it the total displacement over the total time taken, or is it the displacement at the position in question over the total time taken? I have heard all three and am confused.

Any help would be greatly appreciated.

Chocolatepistachio

  • Science Games: Silver
  • Forum Obsessive
  • ***
  • Posts: 470
  • Respect: +51
Re: VCE Physics Question Thread!
« Reply #2369 on: August 24, 2020, 09:38:26 pm »
+2
I think to calculate the average velocity it’s the total displacement divided by the total time taken