Mega A Level Maths Thread MK II

Well the thing I tend to struggle with is the Work-energy principle as I'd rather just use M1 techniques as I can't get the concept straight in my head yet, everything else tends to be alright

Ah yes the work-energy principle, I can't say I remember how to do it but I remember that I didn't know how to do it properly when we covered it in class, and then I went over it at home during revision and it made sense, what about it do you not understand?

Yeah its quite annoying for me really and I understand the equations for the 2 different parts of Gain/Loss in PE = mgh where h is the vertical height and where the Gain/Loss in KE = 1/2mu^2, the main problem I find I have is working out when Work is done by friction on which side it goes on, after I've got that sorted then I'll have that entire part down and they shouldn't really throw me off if one came up in June.

Oh yeah ok I remember, just remember if it's an inclined plane, then in the ball is going up the slope, friction is acting down the slope, if the ball is falling down the slope, friction is acting up the slope

Oh okay, so is the work done by friction just in the direction that friction acts upon?

So for an example if you're going up the plane the equation would be
Loss in KE = Gain in PE + WD by friction? Or would the work done be on the other side of the equation?

85 is pretty good! Erm the moments definitely get more complicated, but there is a pattern to the questions which makes it easier

Hey it can never be in the other side of the equation (and still be positive). The LHS is the energy that will be transferred and the RHS is the energy that it has been transferred to. And energy is not a vector quantity so you can neglect any direction.

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Guys I have a question about histograms.... I know the data has to be continuous so there can be no gaps between the class boundaries. Therefore if it's to the nearest pound (for example), then we use the boundary £1.50-£2-50. However, what happens when the data starts at 0? Do we use 0.50-1.50 or just 0-£1.50?Thanks!

Anyone help me on how to finish this q -

It's q6 and there's one final bit to simplify it but I don't understand how it's arrived at it - the answer is y =100x^3


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Can someone help me with S1 .

Watch this exam solution video/ question c

http://http://www.youtube.com/watch?v=A_MDxLz51qM

I don't understand part C. Here's the Question Paper, its Q3 part C

http://http://www.tomred.org/uploads/7/7/8/3/778329/s1_ms_jan_2011.pdf

The sales for the top 75% of months would be the lower quartile and above.

The lower quartile is £7000. This means that the top 75% of months had an amount received of greater than £7000 rather than £10000, so there is no basis for the company's claim.

75% = UQ though ~?????

Is there something as error carried forward? And what do they do?

It means that if you make a mistake at the beginning of a question, or say in part a), and then you use that answer later on to do something else in theory you shouldonly be penalised once if the rest of your method is correct. In general, certainly for AQA they tend to use 'show that' questions if they think you will need the answer later on, don't know what the other exam boards do though.


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