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#### Ionic Doc

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##### Re: Specialist 1/2 Question Thread!
« Reply #285 on: April 24, 2019, 12:30:42 pm »
0
During the first 8 months, baby Felixs weight increased in the ratio 9 : 4. If his birth weight was 3.6 kg, then his weight after 8 months will be?

help
thnx
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#### AlphaZero

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##### Re: Specialist 1/2 Question Thread!
« Reply #286 on: April 24, 2019, 05:53:09 pm »
+2
I'm confused with a few questions regarding sequences and series

1) I need to find the next 3 terms of,
2,-1,4,3,6,-6

2) I'm so confused about the conversion from explicit to recursive relations, for example,
how do you change u(n)=n^2-4n=7 into a recursive relation

3) find the value of a for which (3,a+2,a^2) defines an arithmetic sequence

Hi there,  can I ask where you found Questions 1 and 2 from? You are only required in Specialist Maths to understand arithmetic and geometric sequences and series, and know some details of a few famous sequences, such as Euler's sequence and the Fibonacci sequence.

As for question 3, if  $\{3,\ a+2,\ a^2\}$  defines an arithmetic sequence, then the common difference between successive terms is constant.

Solution
So, we have \begin{align*}&(a+2)-3=a^2-(a+2)\\
\implies &a-1=a^2-a-2\\
\implies &a^2-2a-1=0\\
\implies &a=\frac{2\pm\sqrt{2^2-4(1)(-1)}}{2(1)}\\
\implies &a=1\pm\sqrt{2} \end{align*}
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#### Evolio

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##### Re: Specialist 1/2 Question Thread!
« Reply #287 on: July 09, 2019, 05:04:47 pm »
0
Hi guys!

I was wondering how to do question 3 c (attached below)?
I'm pretty sure they're asking for the vector resolute. So, why are they giving us the magnitude of b and how can I use it to get the vector resolute? Wouldn't they have to give us the vector b?

2019: Biology [41], Mathematical Methods [38]
2020: Literature, Psychology, Specialist Mathematics, Chemistry

#### S_R_K

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##### Re: Specialist 1/2 Question Thread!
« Reply #288 on: July 09, 2019, 06:26:07 pm »
+1
Hi guys!

I was wondering how to do question 3 c (attached below)?
I'm pretty sure they're asking for the vector resolute. So, why are they giving us the magnitude of b and how can I use it to get the vector resolute? Wouldn't they have to give us the vector b?

A vector in the direction of a is ka where k is a real scalar.

In fact, given that you've already found the unit vector in the direction of a in the first part of the question, you should be able to just write down the answer to part (b)....(Hint: what is the magnitude of the vector you find in part (a)(ii)?) No need to use the formula for the vector resolute.
« Last Edit: July 09, 2019, 06:28:44 pm by S_R_K »

#### Evolio

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##### Re: Specialist 1/2 Question Thread!
« Reply #289 on: July 10, 2019, 03:24:03 pm »
0
Thank you for your help. I understand now!

I was also wondering how to do question 8 b (attached below)? I'm not sure how to approach it.
2019: Biology [41], Mathematical Methods [38]
2020: Literature, Psychology, Specialist Mathematics, Chemistry

#### S_R_K

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##### Re: Specialist 1/2 Question Thread!
« Reply #290 on: July 11, 2019, 01:13:26 am »
0
Thank you for your help. I understand now!

I was also wondering how to do question 8 b (attached below)? I'm not sure how to approach it.

If v is the component of a in the direction of b, then a  v is the component perpendicular to b.

#### Evolio

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##### Re: Specialist 1/2 Question Thread!
« Reply #291 on: July 11, 2019, 08:21:38 am »
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If v is the component of a in the direction of b, then a  v is the component perpendicular to b.
Yeah but how do you know that and how did you get there?
2019: Biology [41], Mathematical Methods [38]
2020: Literature, Psychology, Specialist Mathematics, Chemistry

#### S_R_K

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##### Re: Specialist 1/2 Question Thread!
« Reply #292 on: July 11, 2019, 09:25:20 am »
+1
Yeah but how do you know that and how did you get there?

Sorry my previous post was a bit imprecise.

There are infinitely many ways to resolve a into components such that one of them is parallel to b. We can always write a = kb + (a  kb), where k is any real scalar. Hence, if you have a vector v that is known to be a component of a parallel to b, then the other component must be a  v.

However, this other component is not necessarily perpendicular to b. That other component will only be perpendicular to b if v is the projection of a onto b  this is what the formula for the vector resolute gives you. Hence if v is known to be the vector resolute of a in the direction of b, then a  v must be perpendicular to b.

This image illustrates the idea: https://upload.wikimedia.org/wikipedia/commons/9/98/Projection_and_rejection.png

#### Evolio

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##### Re: Specialist 1/2 Question Thread!
« Reply #293 on: July 11, 2019, 02:55:44 pm »
-1
Thank you for your help, S_R_K!

« Last Edit: July 11, 2019, 02:58:37 pm by Evolio »
2019: Biology [41], Mathematical Methods [38]
2020: Literature, Psychology, Specialist Mathematics, Chemistry

#### ^^^111^^^

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##### Re: Specialist 1/2 Question Thread!
« Reply #294 on: July 13, 2019, 10:05:21 am »
0
Hey there, I am usually never stuck with questions like this (sorry for the low difficulty I know it is kind of dumb  )

Here it is:

The distance travelled (s) by a particle varies partly with time and partly with the square of time. If it travels 142.5 m in 3 seconds and travels 262.5 m in 5 seconds, find:

a) how far it would travel in 6 seconds
b) how far it would travel during the sixth second.

I managed to do question a through part variation formula, but I don't understand the difference between question a and b. I checked the answer key and there were different answers for a and b

Thank you much appreciated

#### AlphaZero

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##### Re: Specialist 1/2 Question Thread!
« Reply #295 on: July 13, 2019, 12:39:09 pm »
+3
Hey there, I am usually never stuck with questions like this (sorry for the low difficulty I know it is kind of dumb  )
...
I managed to do question a through part variation formula, but I don't understand the difference between question a and b. I checked the answer key and there were different answers for a and b
...

Never be afraid to ask questions regardless of the difficulty.

"During the sixth second" actually refers to the time between  $t=5$  and  $t=6$.

Think about it this way. The first second is between  $t=0$  and  $t=1$,  the second second is between  $t=1$  and  $t=2$,  and so on.
2015$-$2017:  VCE
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#### Evolio

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##### Re: Specialist 1/2 Question Thread!
« Reply #296 on: September 01, 2019, 08:52:49 am »
0
Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

2019: Biology [41], Mathematical Methods [38]
2020: Literature, Psychology, Specialist Mathematics, Chemistry

#### S_R_K

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##### Re: Specialist 1/2 Question Thread!
« Reply #297 on: September 01, 2019, 04:56:28 pm »
+2
Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

Let a be the magnitude of acceleration of each mass; let T be the tension in the string. Writing an equation of motion (ie. using F = ma) for each mass we have:

1: 50a = T
2: 20a = 20g  T.

Adding equations gives 70a = 20g, so the acceleration of each mass is 2g/7. Hence the speed of each mass is 2gt/7, where t is in seconds.

#### Helish

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##### Re: Specialist 1/2 Question Thread!
« Reply #298 on: September 01, 2019, 04:57:42 pm »
0
Hey, guys,
Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

Never be afraid to ask questions regardless of the difficulty.

"During the sixth second" actually refers to the time between  $t=5$  and  $t=6$.

Think about it this way. The first second is between  $t=0$  and  $t=1$,  the second second is between  $t=1$  and  $t=2$,  and so on.
Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

Hi guys!
I was wondering how to do the question attached below?
I'm not sure how to go about working it out as the question just gave us the weights. Is this enough info to work this out?

Never be afraid to ask questions regardless of the difficulty.

"During the sixth second" actually refers to the time between  $t=5$  and  $t=6$.

Think about it this way. The first second is between  $t=0$  and  $t=1$,  the second second is between  $t=1$  and  $t=2$,  and so on.
Hey there, I am usually never stuck with questions like this (sorry for the low difficulty I know it is kind of dumb  )

Here it is:

The distance travelled (s) by a particle varies partly with time and partly with the square of time. If it travels 142.5 m in 3 seconds and travels 262.5 m in 5 seconds, find:

a) how far it would travel in 6 seconds
b) how far it would travel during the sixth second.

I managed to do question a through part variation formula, but I don't understand the difference between question a and b. I checked the answer key and there were different answers for a and b

Thank you much appreciated
If v is the component of a in the direction of b, then a  v is the component perpendicular to b.
Hi guys!

I was wondering how to do question 3 c (attached below)?
I'm pretty sure they're asking for the vector resolute. So, why are they giving us the magnitude of b and how can I use it to get the vector resolute? Wouldn't they have to give us the vector b?

I am currently in year 10 doing 1 and 2 business management. next year I am hoping to do eng 1&2 methodes1&2 chem1&2 business management 3&4 and specialist 1&2. I also want to do physics so I thought after I complete Business management, in year 12 I'll do physics 3&4 without 1&2. But teachers said that really hard, so now I am confused in doing physics 1&2 in year 11 and not do spec at all. Is it worth it or not. In my career I want to do medicine or astrophysicist, I really need help guys.

#### ^^^111^^^

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##### Re: Specialist 1/2 Question Thread!
« Reply #299 on: September 01, 2019, 08:41:05 pm »
0
Hey, guys, I am currently in year 10 doing 1 and 2 business management. next year I am hoping to do eng 1&2 methodes1&2 chem1&2 business management 3&4 and specialist 1&2. I also want to do physics so I thought after I complete Business management, in year 12 I'll do physics 3&4 without 1&2. But teachers said that really hard, so now I am confused in doing physics 1&2 in year 11 and not do spec at all. Is it worth it or not. In my career I want to do medicine or astrophysicist, I really need help guys.
There are many factors that need to be taken into account. For example:
- Do you feel like Spec is right for you? I mean, are you capable of handling methods and spesh? If you feel like you enjoy maths in general and you are willing to put in enough hard work (I had to anyway) then from what I know you should be fine.
- You said you wanted to do medicine right, then have you ever thought of doing bio?
- Are specialist and/or methods prerequisites for your aspiring university course?
As for Physics units 3/4 without 1/2, I can't say much, but from what I know if you have enough determination it is possible to do it. But let me just warn you that you will be at a disadvantage (depends on your school as well tho), as some concepts of physics units 3/4 (like for example my textbook relies on prior knowledge to study the concepts like magnetic flux and stuff),need prior knowledge from units 1/2. but DW, the disadvantage is not relatively large.
« Last Edit: September 01, 2019, 09:13:50 pm by ^^^111^^^ »