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Author Topic: Foolproof Method for Maths Questions  (Read 10123 times)  Share 

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jakesilove

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Foolproof Method for Maths Questions
« on: February 26, 2016, 08:44:29 am »
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Often, in Physics or any other Science, the maths questions are the hardest. Where do I even start? Which formulas should I apply? How do I know if I’m using the right method?

There’s no way that you are always going to know how to attack a question, when you first look at it. No matter how many past papers you’ve done, you’ll still get questions that absolutely stump you. Therefore, it is really useful to go into any exam with a method for dealing with tricky questions, especially ones where you don’t even know where to start.

Follow these simple steps to make sure you gain at least a few marks, if not full marks, from literally any maths question in Science!

At the bottom, I have attached a "Supplementary" formula sheet for Physics, with formulas not found on your Formulas sheet! A special thank you goes out to Happy Physics Land, for helping me put it together!

1.   Write out the information you are given in Scientific terms, and identify what you are trying to find.

This is by far the easiest step, as it hardly requires any thinking at all. When I say Scientific terms, I mean the units/notation used in the formulas on your formula sheet. The importance of this step is to allow you to easily decide which formulas to use, by checking which pieces of information you have and using whichever formula seems to work.
Let’s use a Projectile Motion question as an example.

A toy bird is launched at an angle of 600 to the horizontal, and just hits the base of a cliff above it. The cliff is 60m above the toy bird initially, and 40 away (horizontally) from the toy bird initially. Find the initial velocity of the toy bird.

So, let’s rewrite the information we have in Scientific terms, as well as identify what we are trying to find.

           

Great! Now, later on in the question, it will become super easy to figure out which formulas to use.

2.   Apply any mathematical steps that you just HAVE to do, depending on the question type

Most questions just require you to take certain steps. Particularly, in Projectile motion it is common for students to be required to draw a triangle to discern the initial velocities in the horizontal and vertical directions.

In this case, that will look like this:


Now, we can start to attack the actual question!

3.   Apply whichever formulas seem to incorporate as many pieces of information as possible!

Once you’ve done the two above step, you can answer any question with intuitive guess-and-check (for questions which you have no idea how to approach). For instance, in the above question I can see that we have an x distance and an initial velocity in the x direction, therefore I can apply the formula





Okay, now I don’t know if this is useful in any way or not, but let’s just to apply another formula that incorporates more information and see what happens.

Let’s see if



Is useful at all!






Amazing! By literally just randomly subbing in numbers, we got to an answer! The trick is to select equations that seem to contain the information you’ve been given.

4.   Think about units and significant figures.

This step is absolutely crucial to any student looking for full marks. Make sure you’ve used the number of significant figures that equates to the LOWEST you’ve been given, and that your units are in standard SI units.

In this question, the answer could either be

(2 sig figs)

Or

(1 sig fig)

Depending on whether you decide that the values are to 1 or 2 significant figures. Both are correct, but just make sure to put the number of sig figs you used in brackets after the answer.

And there you have it! A foolproof way to attack any maths question in Physics, or any other Science subject!


To ask a question, just make an ATAR Notes account here. and post it below! I'd be happy to help out in any way I can  ;D
« Last Edit: October 30, 2016, 10:36:33 am by jakesilove »
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amyyzhang99

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Re: Foolproof Method for Maths Questions
« Reply #1 on: February 26, 2016, 08:56:28 pm »
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There's something wrong with the post!

Happy Physics Land

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Re: Foolproof Method for Maths Questions
« Reply #2 on: February 27, 2016, 06:02:23 pm »
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There's something wrong with the post!

Hey Amy:

It's probably a LaTex Error or perhaps your web browser doesnt support this type of text type. I've attached a screenshot of the faulty section for you. Sorry if this was a technical error!



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coolala

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Re: Foolproof Method for Maths Questions
« Reply #3 on: February 29, 2016, 09:00:05 pm »
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Is that really all of the equations for hsc?

jamonwindeyer

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Re: Foolproof Method for Maths Questions
« Reply #4 on: February 29, 2016, 09:56:13 pm »
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Is that really all of the equations for hsc?

Pretty much! There are some more from Prelim that could be handy to know, plus those for your elective  ;D

RuiAce

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Re: Foolproof Method for Maths Questions
« Reply #5 on: July 09, 2016, 05:16:35 pm »
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#5: If units are used correctly, units substituted also CANCEL OUT in rearranging.

jamonwindeyer

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Re: Foolproof Method for Maths Questions
« Reply #6 on: July 09, 2016, 10:52:28 pm »
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#5: If units are used correctly, units substituted also CANCEL OUT in rearranging.

I love this, taught it properly at uni as an actual part of the method, but so handy for checking calculations!  ;D

m_chan98

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Re: Foolproof Method for Maths Questions
« Reply #7 on: August 17, 2016, 12:36:38 pm »
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So I made a HUGE mistake in my Physics trial by forgetting to take my calculator into the exam room with me and I didn't realise until the exam had actually started. I still did all the maths questions, but I only had formulas and substitutions and not an actual answer.
Most maths questions were 3 markers, would I still get at least 1 or 2 marks out of them?
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RuiAce

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Re: Foolproof Method for Maths Questions
« Reply #8 on: August 17, 2016, 12:52:23 pm »
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So I made a HUGE mistake in my Physics trial by forgetting to take my calculator into the exam room with me and I didn't realise until the exam had actually started. I still did all the maths questions, but I only had formulas and substitutions and not an actual answer.
Most maths questions were 3 markers, would I still get at least 1 or 2 marks out of them?
Yes. If you can demonstrate that you can use the correct formula with correct substitutions, you get a part of the marks available.

jamonwindeyer

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Re: Foolproof Method for Maths Questions
« Reply #9 on: August 17, 2016, 01:44:33 pm »
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So I made a HUGE mistake in my Physics trial by forgetting to take my calculator into the exam room with me and I didn't realise until the exam had actually started. I still did all the maths questions, but I only had formulas and substitutions and not an actual answer.
Most maths questions were 3 markers, would I still get at least 1 or 2 marks out of them?

Damn! What a bummer, good on you for still making sure to maximise your efforts in the room! If it was a 3 marker, you should get two marks out of the three, as long as you showed all your working. If the only line missing was the solution itself, you'll get 2 marks! ;D

Sanaz

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Re: Foolproof Method for Maths Questions
« Reply #10 on: October 27, 2016, 03:38:15 pm »
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Hey :) Not sure what I'm missing in this question. What is the working out for this question?

Cindy2k16

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Re: Foolproof Method for Maths Questions
« Reply #11 on: October 27, 2016, 03:47:57 pm »
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Hey :) Not sure what I'm missing in this question. What is the working out for this question?

hi so you work out the vertical velocity after 2 seconds.
Since initial vertical velocity is 0 (it only has horizontal velocity initially) then using the formula v=u +at and subbing in u=0, a=9.8 and t=2, you get that the vertical velocity is 19.6m/s downwards.
Then you draw the triangle with the 45 angle and the 19.6 on the opposite side. Then using sintheta=O/H you sub in theta=45, O=19.6 and H is the resultant velocity. Rearrange the equation and you'll work out that the velocity is 27.7 m/s. So, D
Hope this helps
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Sanaz

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Re: Foolproof Method for Maths Questions
« Reply #12 on: October 27, 2016, 03:57:34 pm »
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hi so you work out the vertical velocity after 2 seconds.
Since initial vertical velocity is 0 (it only has horizontal velocity initially) then using the formula v=u +at and subbing in u=0, a=9.8 and t=2, you get that the vertical velocity is 19.6m/s downwards.
Then you draw the triangle with the 45 angle and the 19.6 on the opposite side. Then using sintheta=O/H you sub in theta=45, O=19.6 and H is the resultant velocity. Rearrange the equation and you'll work out that the velocity is 27.7 m/s. So, D
Hope this helps

Oh yea haha now I realised where i went wrong, I was trying to find the x component of velocity and there wasn't enough info. But i didn't really need it :P Thanks for helping me!

strong1739

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Re: Foolproof Method for Maths Questions
« Reply #13 on: October 29, 2016, 11:24:40 pm »
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how did you get tan?????? idk what im doing

RuiAce

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Re: Foolproof Method for Maths Questions
« Reply #14 on: October 29, 2016, 11:25:45 pm »
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how did you get tan?????? idk what im doing