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March 29, 2024, 04:34:03 pm

Author Topic: VCE Specialist 3/4 Question Thread!  (Read 2164545 times)  Share 

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knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8325 on: September 26, 2016, 08:20:01 am »
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For this question and answer attached.

How are we expected to show forces on an object?

In my diagram i label the forces acting from the centre of the object, is this fine ? (image is attached)

RuiAce

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Re: Specialist 3/4 Question Thread!
« Reply #8326 on: September 26, 2016, 08:38:13 am »
+1
For this question and answer attached.

How are we expected to show forces on an object?

In my diagram i label the forces acting from the centre of the object, is this fine ? (image is attached)

If you ask me yes that's fine. That's what I would've done for HSC mechanics questions.

Best let a VCE-er confirm though.

knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8327 on: September 26, 2016, 11:54:20 am »
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If you ask me yes that's fine. That's what I would've done for HSC mechanics questions.

Best let a VCE-er confirm though.

Thanks RuiAce !  :)

Jayz2398

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Re: Specialist 3/4 Question Thread!
« Reply #8328 on: September 26, 2016, 01:46:10 pm »
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Hey all,

In doing the first mechanics question from SM 2015 Checkpoints (A7 195), I've found a force via the sine rule and written it as follows:

The actual answer is:

In CAS, simplifying the first form gives the second one.
But the problem is that I'm not sure how to simplify the first form to obtain the second one by hand. Would anyone be able to help me out?

Thanks,
Jack

RuiAce

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Re: Specialist 3/4 Question Thread!
« Reply #8329 on: September 26, 2016, 01:47:33 pm »
+1
Hey all,

In doing the first mechanics question from SM 2015 Checkpoints (A7 195), I've found a force via the sine rule and written it as follows:

The actual answer is:

In CAS, simplifying the first form gives the second one.
But the problem is that I'm not sure how to simplify the first form to obtain the second one by hand. Would anyone be able to help me out?

Thanks,
Jack
« Last Edit: September 26, 2016, 01:51:17 pm by RuiAce »

Jayz2398

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Re: Specialist 3/4 Question Thread!
« Reply #8330 on: September 26, 2016, 02:09:49 pm »
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Thank you! :)

lzxnl

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Re: Specialist 3/4 Question Thread!
« Reply #8331 on: September 27, 2016, 09:46:49 pm »
0
Hey all,

In doing the first mechanics question from SM 2015 Checkpoints (A7 195), I've found a force via the sine rule and written it as follows:

The actual answer is:

In CAS, simplifying the first form gives the second one.
But the problem is that I'm not sure how to simplify the first form to obtain the second one by hand. Would anyone be able to help me out?

Thanks,
Jack

Your second term is negative. Just saying.
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Jayz2398

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Re: Specialist 3/4 Question Thread!
« Reply #8332 on: September 30, 2016, 02:02:46 pm »
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Your second term is negative. Just saying.

Oh yikes! Thanks, I missed that.

Jayz2398

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Re: Specialist 3/4 Question Thread!
« Reply #8333 on: September 30, 2016, 02:11:58 pm »
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I've got a couple more questions if you're still happy to help me out.

The first one is another Mechanics Q (CP2015 A7 Q212).

I've done some working here which reaches one of the MC options, but it's not the correct one. I understand how the alternative method of resolving components works, but I'm not sure about why my method doesn't work.


The next question is from complex no. (CP2015 A2 Q32c). I'm sorta completely lost on the 'show that these are the only possible values' part, and also not entirely sure on the book's solutions due to the inclusion of z=+/- 2 (namely where it comes from and why it's useful).





Thank you!

Syndicate

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Re: Specialist 3/4 Question Thread!
« Reply #8334 on: September 30, 2016, 03:07:56 pm »
+1
I've got a couple more questions if you're still happy to help me out.

The first one is another Mechanics Q (CP2015 A7 Q212).
(Image removed from quote.)
I've done some working here which reaches one of the MC options, but it's not the correct one. I understand how the alternative method of resolving components works, but I'm not sure about why my method doesn't work.
(Image removed from quote.)

The next question is from complex no. (CP2015 A2 Q32c). I'm sorta completely lost on the 'show that these are the only possible values' part, and also not entirely sure on the book's solutions due to the inclusion of z=+/- 2 (namely where it comes from and why it's useful).

(Image removed from quote.)

(Image removed from quote.)

Thank you!

1) Sine rule only applies to non-right angled triangles. Here we have a case involving a right angled triangle.









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Jayz2398

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Re: Specialist 3/4 Question Thread!
« Reply #8335 on: September 30, 2016, 08:53:03 pm »
+2

1) Sine rule only applies to non-right angled triangles. Here we have a case involving a right angled triangle.









Ahh I think I get it. My triangle is wrong anyway, because I labelled the angles 30, 30 and 90 (sum is not 180 - silly me).

But shouldn't the sine rule work for right-angled triangles anyway? If the right angle is used in the sine rule, sin(90°) becomes 1, and I thought that'd leave a trig equation sin(something) = a/b.

Syndicate

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Re: Specialist 3/4 Question Thread!
« Reply #8336 on: October 01, 2016, 12:56:02 pm »
+1
But shouldn't the sine rule work for right-angled triangles anyway? If the right angle is used in the sine rule, sin(90°) becomes 1, and I thought that'd leave a trig equation sin(something) = a/b.

Yes, you are correct (sorry for my erroneous statement). Although, the sine rule can be applied in such conditions, an astute student would use basic trigonometry to solve for T (since it would save time).
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MightyBeh

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Re: Specialist 3/4 Question Thread!
« Reply #8337 on: October 01, 2016, 01:38:18 pm »
+1
The next question is from complex no. (CP2015 A2 Q32c). I'm sorta completely lost on the 'show that these are the only possible values' part, and also not entirely sure on the book's solutions due to the inclusion of z=+/- 2 (namely where it comes from and why it's useful).

(Image removed from quote.)

(Image removed from quote.)

Thank you!
To find the +/- 2, consider the following:

The non real solutions come from the previous parts of the question. We couldn't find this solution in part b. because we were solving specifically for a, which is a non-real because it's the coefficient of i. We need to consider real solutions here because p(z) is a cubic with real constants (conjugate root theorem). After that you just sub in your solutions and solve like in the book's solution. hmu if that's not clear :)
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blacksanta62

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Re: Specialist 3/4 Question Thread!
« Reply #8338 on: October 03, 2016, 07:28:02 pm »
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Can anyone help me out with the attached question? I keep getting a different answer to what they get. Also, I'm not using Z scores (cause I don't know how they work, rather I'm using normalcdf on the CAS)
Also, how do I know when to use a one tail approach or a two tail approach in a question? They won't explicitly tell me will they?
And what's the best way to prepare for a stats SAC? What approach did you use? Just doing the extended response at the back of the cambridge book? My teacher likes to use MAV SACs which I just find really hard!
Thanks
Edit: If it's important, the first p-score I got was 1.736 and the second was 0.5646
The answer is 0.2636
« Last Edit: October 03, 2016, 07:29:54 pm by blacksanta62 »
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knightrider

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Re: Specialist 3/4 Question Thread!
« Reply #8339 on: October 04, 2016, 09:27:12 am »
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How would you do this question ?

The time for a customer to be served at a fast-food outlet is normally distributed with a mean of 3.5 minutes and a standard deviation of 1.0 minutes. What is the probability that 20 customers can be served in less than one hour?