Hey there! Sign in to join this conversationNew here? Join for free
    Offline

    1
    ReputationRep:
    (Original post by Smaug123)
    I explained it to my friends mid-AS year, and it would have been very useful to me to know earlier… (I only realised it was the same thing as dimensional analysis at the start of A2-year.)
    Smaug- I assume that you have finished your Alevels?

    Would you mind giving me some advice?

    1. I have finished all the pastpapers and most of the textbook questions for Maths- what do I do now? :lol:

    2.Did you do Biology Alevel? I think I am doomed for it.
    Offline

    14
    ReputationRep:
    You can't be awful at maths. Either you have a rubbish teacher or you don't have enough practise.
    Offline

    21
    ReputationRep:
    (Original post by Smaug123)
    I explained it to my friends mid-AS year, and it would have been very useful to me to know earlier… (I only realised it was the same thing as dimensional analysis at the start of A2-year.)
    Would take a large amount of care to remember you and this post a couple of years from now.
    • PS Helper
    • Study Helper
    Offline

    13
    ReputationRep:
    PS Helper
    Study Helper
    (Original post by upthegunners)
    I doubt the 15 year kid would understand the first part (Because I don't :lol:) All I know is that it's Newtons inverse square law on gravity.
    :P yeah, the first part was meant to be a whistlestop tour - maybe it was a bit too whistlestop :P


    (Original post by upthegunners)
    Smaug- I assume that you have finished your Alevels?

    Would you mind giving me some advice?

    1. I have finished all the pastpapers and most of the textbook questions for Maths- what do I do now? :lol:

    2.Did you do Biology Alevel? I think I am doomed for it.
    I didn't do Biology, I'm afraid I know almost nothing about it! I've finished my A-levels, yep - for maths, I can only recommend doing all the past papers, but you've done that! Sounds like you should be fine start doing them again if you've run out of stuff to do
    (Original post by ozzyoscy)
    Would take a large amount of care to remember you and this post a couple of years from now.
    I'm afraid I don't understand this… as in, literally can't parse it, not "the sentiment behind it is alien to me" - could you rephrase please?
    Offline

    0
    ReputationRep:
    I used this dimensional analysis semi unwittingly at GCSE and it helped far more than anything else, remember there is no substitute for hard work though


    Posted from TSR Mobile
    Offline

    18
    ReputationRep:
    (Original post by Smaug123)
    An awful lot of physics-maths can be done with the posh-sounding technique of dimensional analysis (known to us mere mortals as "juggling the units"). Basically you can work out all the formulae just by matching up the units - for example, given that G has units N m^2 / kg^2, you can instantly construct the formula \frac{G m_1 m_2}{r^2} = F where m_i are masses and r is a distance, since the thing on top of the fraction has units N m^2, the thing on the bottom has units m^2, so the whole thing has units N, which is the unit of force. (This formula is bound to be right up to a function of a unitless thing, so it might differ by a multiple of \frac{m_1}{m_2} from the actual formula, or by a constant - in this case it turns out not to.) Without even knowing what the formula means, you can shove an idea of a formula together, and if you know what it means (the gravitational force between two objects) then you can verify that it's correct (for instance, that r^2 is really r^2 and not r_1 r_2, because there's only one distance between two objects).
    If you just make sure you write units next to *everything*, even silly units like "5 bananas", then you can work things out. Simple example: A person eats five bananas every second, and eats for ten seconds; how many bananas has she eaten? Don't be tempted to write your answer as a number, because that tells you nothing. You're looking for an answer in bananas; you have the inputs "5 bananas/second"; "10 second", how can I combine them to make "bananas"? It's clear from looking at the units that you have to multiply them (since "banana/second * second = banana"). So the answer is 50 bananas.
    It's surprising just how far this technique gets you (at A-level and beyond!)
    I didn't know the specific name for this technique, but surely everyone does this? I've been doing this for Physics since the start of year 10, most people I know have too... it's just pretty obvious tbh.

    Either way, OP said his "physics-maths" was pretty good, he wants help with "maths-maths"
    • PS Helper
    • Study Helper
    Offline

    13
    ReputationRep:
    PS Helper
    Study Helper
    (Original post by justinawe)
    I didn't know the specific name for this technique, but surely everyone does this? I've been doing this for Physics since the start of year 10, most people I know have too... it's just pretty obvious tbh.

    Either way, OP said his "physics-maths" was pretty good, he wants help with "maths-maths"
    It surprised me to find out that no-one else in my class used it, and only a few people in my year did.
    I think I sort of misunderstood in some way - goodness knows how I managed to read the OP as saying "I can do all the GCSE physics no problem, but when it comes to the more mathsy stuff at A-level, I find it hard"… perhaps I need to slow down! Oops…
    Offline

    1
    ReputationRep:
    OP- you are not bad at Maths

    you just think you are bad at Maths
    Offline

    18
    ReputationRep:
    (Original post by upthegunners)
    OP- you are not bad at Maths

    you just think you are bad at Maths
    This might be right. I used to think I was bad at maths until it was explained to me that it's only 20% natural aptitude. The other 90% is just hard work and attention to detail.
    • PS Helper
    • Study Helper
    Offline

    13
    ReputationRep:
    PS Helper
    Study Helper
    (Original post by cambio wechsel)
    This might be right. I used to think I was bad at maths until it was explained to me that it's only 20% natural aptitude. The other 90% is just hard work and attention to detail.
    love it! Do you mind if I pinch this as a quote?
    • Study Helper
    Offline

    21
    ReputationRep:
    Study Helper
    (Original post by Smaug123)
    love it! Do you mind if I pinch this as a quote?
    And as Thomas Edison said, "since genius is 1% inspiration and you need a good deodorant for the perspiration".
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.