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October 02, 2025, 03:45:17 am
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Author Topic: VCE Specialist 3/4 Question Thread!  (Read 2612652 times)  Share 

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Apink!

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Re: Specialist 3/4 Question Thread!
« Reply #8145 on: July 15, 2016, 01:33:32 am »
0
Thank you :)

EDIT: Sorry lzxnl, but after thinking for a bit, I don't think I understand why the tension has to be larger than m1g because m1 is moving up and m2 moving down. Do you mind clarifying that for me? Sorry about that!
Quote from: lzxnl on July 15, 2016, 12:58:38 am
Well if m2>m1, the m2 mass is moving down and the m1 mass is moving up. This means that the tension force must be greater than m1g.

As for friction, F = uN when it's moving, but the coefficient of friction is a coefficient of kinetic friction, whereas Fmax = uN for verge of moving has a coefficient of static friction; the former is generally smaller than the latter. If something is on the verge of moving, they WILL tell you. Something at rest on a slanted slide isn't on the verge of moving though; the friction force then might not be at its maximum.
« Last Edit: July 15, 2016, 02:03:18 am by Apink! »
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HighTide

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Re: Specialist 3/4 Question Thread!
« Reply #8146 on: July 15, 2016, 08:53:30 am »
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Quote from: Apink! on July 15, 2016, 01:33:32 am
Thank you :)

EDIT: Sorry lzxnl, but after thinking for a bit, I don't think I understand why the tension has to be larger than m1g because m1 is moving up and m2 moving down. Do you mind clarifying that for me? Sorry about that!
Since m2 > m1, you know that m2 must go down, and m1 must go up.
The formula for the m1 is m1a= T - m1g
This is in the upward direction. So in order for mass 1 to accelerate upwards, m1a > 0    T>m1g
If m1 > m2, then you have m1 going downwards, and you'd have T > m2g.
And in the situation where it was at equilibrium, you would have T= m1g.

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knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8147 on: July 16, 2016, 06:27:22 pm »
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How would you convert 12960 km/h^2 to m/s^2 ?
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RuiAce

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Re: Specialist 3/4 Question Thread!
« Reply #8148 on: July 16, 2016, 06:41:53 pm »
+1
Quote from: knightrider on July 16, 2016, 06:27:22 pm
How would you convert 12960 km/h^2 to m/s^2 ?
12960 km/h2 means 12960000m/h2

1 hr2 = 36002 s2

12960000/36002=1

Therefore 1 m/s2
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keltingmeith

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Re: Specialist 3/4 Question Thread!
« Reply #8149 on: July 16, 2016, 06:44:18 pm »
+1
Quote from: knightrider on July 16, 2016, 06:27:22 pm
How would you convert 12960 km/h^2 to m/s^2 ?

Short answer: divide by 12,960 (there's a reason they've asked you to convert that number :P)

Long answer which shows off some things you learned about in related rates: (and goes into what RuiAce did in more detail)

1,000m in a km, and 60 seconds in a minute, 60 minutes in an hour.

So, this gives us the following conversion factors:

1,000 m/km, and 60 seconds/minute, 60 minutes/hour.

Combining the last two, we get:

60 seconds/minutes * 60 minutes/hour = 3,600 seconds/hour

So, we use our first conversion factor to change the km into m:

12,960 km/h^2, 1,000 m/km
----> 12,960 km/h^2 * 1,000 m/km = 12,960,000 m/h^2

Now we use our second to convert the hours into seconds. However, our units won't match! so instead, we need to flip 3,600:

12,960,000 m/h^2 * 1/(3,600 s/h ) = 12,960,000 m/h^2 * (1/3600) h/s = 3,600 m/hs

Oops, we only got rid of ONE of the hours! Looks like we'll have to do it one more time:

3,600 m/hs * (1/3600) h/s = 1 m/s^2

And that's all there is to it! Units are our friends~
« Last Edit: July 16, 2016, 09:01:42 pm by melting meithy »
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RuiAce

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Re: Specialist 3/4 Question Thread!
« Reply #8150 on: July 16, 2016, 06:46:46 pm »
+2
Never thought about using related rates with units. I just convert using what I have in front of me lol.
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lzxnl

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Re: Specialist 3/4 Question Thread!
« Reply #8151 on: July 16, 2016, 11:27:56 pm »
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Quote from: RuiAce on July 16, 2016, 06:46:46 pm
Never thought about using related rates with units. I just convert using what I have in front of me lol.


I do it that way too, for what it's worth. It's foolproof (as long as you can manipulate indices)
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knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8152 on: July 17, 2016, 06:41:05 pm »
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Quote from: RuiAce on July 16, 2016, 06:41:53 pm
12960 km/h2 means 12960000m/h2

1 hr2 = 36002 s2

12960000/36002=1

Therefore 1 m/s2

Quote from: melting meithy on July 16, 2016, 06:44:18 pm
Short answer: divide by 12,960 (there's a reason they've asked you to convert that number :P)

Long answer which shows off some things you learned about in related rates: (and goes into what RuiAce did in more detail)

1,000m in a km, and 60 seconds in a minute, 60 minutes in an hour.

So, this gives us the following conversion factors:

1,000 m/km, and 60 seconds/minute, 60 minutes/hour.

Combining the last two, we get:

60 seconds/minutes * 60 minutes/hour = 3,600 seconds/hour

So, we use our first conversion factor to change the km into m:

12,960 km/h^2, 1,000 m/km
----> 12,960 km/h^2 * 1,000 m/km = 12,960,000 m/h^2

Now we use our second to convert the hours into seconds. However, our units won't match! so instead, we need to flip 3,600:

12,960,000 m/h^2 * 1/(3,600 s/h ) = 12,960,000 m/h^2 * (1/3600) h/s = 3,600 m/hs

Oops, we only got rid of ONE of the hours! Looks like we'll have to do it one more time:

3,600 m/hs * (1/3600) h/s = 1 m/s^2

And that's all there is to it! Units are our friends~

Quote from: RuiAce on July 16, 2016, 06:46:46 pm
Never thought about using related rates with units. I just convert using what I have in front of me lol.


Thanks so much RuiAce  :) and melting meithy  :) !!! Makes sense now !!
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Callum@1373

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Re: Specialist 3/4 Question Thread!
« Reply #8153 on: July 19, 2016, 05:35:06 pm »
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For the question attached, how is the answer B? Because that implies that with 4(y-3) on the denominator, when y = 3 the denominator is 0 and therefore the gradient is infinity and as you can see from the attachment, that's not the case for all x values.
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Exhati

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Re: Specialist 3/4 Question Thread!
« Reply #8154 on: July 20, 2016, 10:02:41 pm »
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does anyone know if collinear vectors are in the study design? There's a chapter in the cambridge txt book but I don't see anything mentioned in the study design and it has been asked in the past.
  cheers
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zsteve

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Re: Specialist 3/4 Question Thread!
« Reply #8155 on: July 20, 2016, 10:06:55 pm »
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Quote from: Exhati on July 20, 2016, 10:02:41 pm
does anyone know if collinear vectors are in the study design? There's a chapter in the cambridge txt book but I don't see anything mentioned in the study design and it has been asked in the past.
  cheers

I think collinear vectors is a result of the more fundamental vector theory that you're taught in Specialist. Hence, although it's not explicitly mentioned in the study design, it's can definitely be assessed.

And it's not that hard anyways :)
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RuiAce

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Re: Specialist 3/4 Question Thread!
« Reply #8156 on: July 20, 2016, 10:07:53 pm »
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Quote from: Exhati on July 20, 2016, 10:02:41 pm
does anyone know if collinear vectors are in the study design? There's a chapter in the cambridge txt book but I don't see anything mentioned in the study design and it has been asked in the past.
  cheers
Do you guys get taught the condition for two vectors to be parallel? Cause if so then I reckon it's fine, because a pair of collinear vectors are just a pair of parallel vectors that coincide.
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knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8157 on: July 24, 2016, 07:23:36 pm »
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When i was doing a question i encountered the follwing statement.

"The particle decelerates exponentially with terminal velocity k m/s ".

What does this statement mean ?
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RuiAce

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Re: Specialist 3/4 Question Thread!
« Reply #8158 on: July 24, 2016, 07:30:13 pm »
+1
Quote from: knightrider on July 24, 2016, 07:23:36 pm
When i was doing a question i encountered the follwing statement.

"The particle decelerates exponentially with terminal velocity k m/s ".

What does this statement mean ?
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knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8159 on: July 24, 2016, 07:41:00 pm »
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Quote from: RuiAce on July 24, 2016, 07:30:13 pm

'Thanks RuiAce  :)

so in the context of this situation would it be a horizontal asymptote ( can i interpret it like this ) ?
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