August 24, 2019, 09:04:40 pm

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#### JeKnYan

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##### Re: VCE Physics Question Thread!
« Reply #2265 on: June 10, 2019, 08:18:43 pm »
0
What's the recommendation on decimal places/sig figs in the exam? I've always been taught it's two, just asking for your two cents

#### Jackson.Sprigg

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##### Re: VCE Physics Question Thread!
« Reply #2266 on: June 11, 2019, 06:21:24 pm »
+2
I believe you should base your significant figures on the most inaccurate measurement in the question.

i.e. If the question gives you 3 values with 2, 3 and 4 sig figs respectively and you use all these values in your working. Then you can only say for certain that your answer is as accurate as the least accurate value you used. In this case it would be the 2 sig figs and so that is how many you would use in your final answer.
« Last Edit: June 11, 2019, 06:34:45 pm by Jackson.Sprigg »

#### Zealous

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##### Re: VCE Physics Question Thread!
« Reply #2267 on: June 14, 2019, 10:08:40 pm »
+1
I believe you should base your significant figures on the most inaccurate measurement in the question.

i.e. If the question gives you 3 values with 2, 3 and 4 sig figs respectively and you use all these values in your working. Then you can only say for certain that your answer is as accurate as the least accurate value you used. In this case it would be the 2 sig figs and so that is how many you would use in your final answer.

Yep, this approach works fine. If you are unsure, usually 3-4 sig figs is more than enough - I'm quite sure the exam markers accept answers within a certain tolerance.
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#### Terrapin

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##### Re: VCE Physics Question Thread!
« Reply #2268 on: June 18, 2019, 10:45:24 am »
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A dodgem car of mass 200 kg is driven due south
into a rigid barrier at an initial speed of 5.0 m s−1.
The dodgem rebounds at a speed of 2.0 m s−1. It is
in contact with the barrier for 0.20 s. Calculate:
(a) the average acceleration of the car during its
interaction with the barrier
(b) the average net force applied to the car during
its interaction with the barrier.

#### Erutepa

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##### Re: VCE Physics Question Thread!
« Reply #2269 on: June 18, 2019, 08:15:52 pm »
+3
A dodgem car of mass 200 kg is driven due south
into a rigid barrier at an initial speed of 5.0 m s−1.
The dodgem rebounds at a speed of 2.0 m s−1. It is
in contact with the barrier for 0.20 s. Calculate:
(a) the average acceleration of the car during its
interaction with the barrier
(b) the average net force applied to the car during
its interaction with the barrier.
Before others weigh in on these questions, it is important that you give them a try first and write down what your current thought processes you have in regards to them. It is important to identify specifically what things you do know and what things you don't know so that you can better learn and people can better explain the questions to fit your own confusions.
And don't worry about getting things wrong - you won't be judged harshly at all.
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#### julia_atarnotes

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##### Re: VCE Physics Question Thread!
« Reply #2270 on: June 29, 2019, 11:56:28 am »
+2
What's the recommendation on decimal places/sig figs in the exam? I've always been taught it's two, just asking for your two cents

Hey! My past physics teacher was an examiner and he said that 2 decimal places is sufficient. Marks will only be taken off if the question asks you specifically to answer to the correct number of significant figures OR if you use too few significant figures eg. rounding 543.67 to 540. Using the "correct" number of significant figures can be tricky because a lot of physics constants that we are given only use 2-3 significant figures (eg. gravity, speed of light) which may not be enough to satisfy your examiner.

#### S200

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##### Re: VCE Physics Question Thread!
« Reply #2271 on: July 03, 2019, 11:27:54 pm »
+4
A dodgem car of mass 200 kg is driven due south
into a rigid barrier at an initial speed of 5.0 m s−1.
The dodgem rebounds at a speed of 2.0 m s−1. It is
in contact with the barrier for 0.20 s. Calculate:
(a) the average acceleration of the car during its
interaction with the barrier
(b) the average net force applied to the car during
its interaction with the barrier.
A.)
Acceleration is defined as the rate of change of velocity, or $\frac {V_I - V_F}{Time}$.
We're given the initial and the final velocities, and also the full time of the collision.
Hence, substitute the values and calculate...
$\frac{5-(-2)}{0.20} = 35ms^{-1}$ in a negative direction, or away from the barrier
B.)
Force is merely $Mass \times Acceleration$. The word 'average' is used to indicate that this is not an 'instantaneous' or precisely measured velocity. Thus, average Force is equal to the mass of the body multiplied by the average velocity over the defined time. $F = m \frac{(v_f - v_i)}{t}.$
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#### eo to

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##### Re: VCE Physics Question Thread!
« Reply #2272 on: July 22, 2019, 09:37:09 pm »
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It's from the Heinemann physics 12 4th edition textbook (chapter 8 review)

#### BAH0003

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##### Re: VCE Physics Question Thread!
« Reply #2273 on: July 23, 2019, 07:06:23 pm »
0
Hi,

Quick question, if anyone cna help that would be great:

"A Subaru travels with a uniform acceleration on a racetrack. It starts from rest and covers 400m in 16s."
What is the cars final speed in km h^-1?

Thanks

#### BAH0003

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##### Re: VCE Physics Question Thread!
« Reply #2274 on: July 23, 2019, 07:40:27 pm »
0
Hi again,

Another question if anyone can answer.

"During its launch phase, a space rocket accelerates
uniformly from rest to 160 m s–1 upwards in 4.0 s,
then travels with a constant speed of 160 m s–1 for the
next 5.0 s"
How far (in km) does the rocket travel in this 9.0 s
period?

Thanks

#### ^^^111^^^

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##### Re: VCE Physics Question Thread!
« Reply #2275 on: July 23, 2019, 07:40:51 pm »
+3
Hi,

Quick question, if anyone cna help that would be great:

"A Subaru travels with a uniform acceleration on a racetrack. It starts from rest and covers 400m in 16s."
What is the cars final speed in km h^-1?

Thanks

Use the kinematic formula v= u+at
v is final speed
u is initial speed
a is acceleration
t is time

initial speed is 0 (at rest) so v=at. The acceleration is 25 m/s. This multiplied by 3600(number of seconds in an hour) = 90,000 meters (ideally it should be written as 90 km. In case you may need it other kinematic formulas are:

v^2 = u^2 + 2as
s = ut + 1/2*[a(t^2)]
s=1/2*(v+u)t
s=vt - 1/2*[a(t^2)]

v is final speed
u is initial speed
s is displacement
a is acceleration
t is time

#### ^^^111^^^

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##### Re: VCE Physics Question Thread!
« Reply #2276 on: July 23, 2019, 07:48:14 pm »
+1
Hi again,

Another question if anyone can answer.

"During its launch phase, a space rocket accelerates
uniformly from rest to 160 m s–1 upwards in 4.0 s,
then travels with a constant speed of 160 m s–1 for the
next 5.0 s"
How far (in km) does the rocket travel in this 9.0 s
period?

Thanks

This time use the kinematic formula s=ut + 1/2[a(t^2)]

Initial speed is zero. acceleration is 160 m/s. Time is 4 seconds. [This is for the first part. I will explain next shortly]. 4^2 = 16. 16 seconds *160 meters/seconds  = 2.56 km

Do the exact same method as before and add the values together to find the displacement of the rocket.

#### milanander

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##### Re: VCE Physics Question Thread!
« Reply #2277 on: July 28, 2019, 09:40:55 pm »
0
Hi, current year 11 here doing physics 1/2. I'm hoping to get a head start for 3/4 next year and was wondering what are some key areas which I should start looking over now? Also what company would everyone recommend for practice exams? Thanks so much.
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#### ^^^111^^^

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##### Re: VCE Physics Question Thread!
« Reply #2278 on: July 28, 2019, 10:24:37 pm »
+1
Hi, current year 11 here doing physics 1/2. I'm hoping to get a head start for 3/4 next year and was wondering what are some key areas which I should start looking over now? Also what company would everyone recommend for practice exams? Thanks so much.

There is not much I can say about this but I am using  the Heinemann Physics 3/4 textbook for Physics , so here I go.

- Heisenberg Uncertainity Principle
- Quantum Mechanics
- Photoelectric Effect
- Circular Motion
- Special Relativity
- Electromagnetic Induction
- Properties of mechanical waves

These are the topics that are supposed to be covered in Units 3/4.  Sorry I don't think I really answered your question completely. It would be great if someone else can have a look at this.

#### redpanda83

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##### Re: VCE Physics Question Thread!
« Reply #2279 on: July 28, 2019, 11:10:20 pm »
+1
Hi, current year 11 here doing physics 1/2. I'm hoping to get a head start for 3/4 next year and was wondering what are some key areas which I should start looking over now? Also what company would everyone recommend for practice exams? Thanks so much.
it would be really good to get head start on newtonian mechanics(classical physics for motion, refering to point 1 mentioned below), which you should be doing as your unit 2 atm or starting.
1. Kinematics, vectors, Forces(newtons laws), Energy(conservation of energy, kinetic energy, GPE, Spring potential energy stuff) momentum and impulse, projectile motion, circular motion.
2. Special Relativity
3. Fields and their patterns, Gravitational Fields, Electric Fields, Magnetic Fields.
4. DC motors, Power generation principles, Transformers and transmission. (this part relates a bit to your electrical circuit component)
5. Light (wave-particle duality) -
(i) light as a wave - wave principles(what is a wave?), wave phenomenon(interference, diffraction, dispersion and
refraction), standing waves (harmonics, look into rubens tube for this its fun!) - light is not dicrete but continuos
(ii) light as particle - photo electric effect (how solar panel works), light is emitted in quantised(discrete) packets of
energy and the amount of energy is dependent of frequency of the photon, how matter can also behave like wave
De Broglie’s wave–particle theory, emission spectra and energy levels of an atom.
I dont really find textbook helpful at all (I have both Jacaranda and Heinmann textbooks), but if you want you can use it as a guide. Khan academy, Lectures by Professor Walter lewins and some other resources are much better. Building things throughout the course will help you further you understanding i think, if you really wanna do it, even little simulations and thought experiments are good.
Hope it helps