AQA A2 Mathematics MPC4 Core 4 - 9th June 2015 [Discussion & unofficial markscheme]

Original post by Jimmy20002012

Wonder what the differential in context will be one this time it's always either ever on paintings or bacteria.

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Or money in a bank or footballers wages.

Reply 1221

Tiwa

7

Done four past papers today in preparation for tomorrow's exam. I'm just going to brush up on any lose info in my revision guide. Not much more I can do. All the best for tomorrow people!

Reply 1222

datpr0

2

Original post by saeed97

New technological advancement has just been released which you could use to find it. Heres the link: google.co.uk

uwotm9?

Reply 1223

Mudkipzz

8

Original post by saeed97

New technological advancement has just been released which you could use to find it. Heres the link: google.co.uk

Yeah I could look at it individually but people in the past have made spreadsheets with just past C4 grade boundaries, also learn to hyperlink.

Reply 1224

2014_GCSE

3

Super easy way to approach Vector questions are diagrams. Makes them so much easier.
Can picture what lengths you are trying to find, where angles are, etc.

Reply 1225

saeed97

5

Original post by Mudkipzz

Yeah I could look at it individually but people in the past have made spreadsheets with just past C4 grade boundaries, also learn to hyperlink.

Sorry, im obviously not skilled in the art of forum hyperlinking.

Reply 1226

saeed97

5

Original post by datpr0

uwotm9?

u wunt sum? i'll giv it 2 u

Reply 1227

RhyaCeri

2

Original post by saeed97

Or money in a bank or footballers wages.

there was one on a colony of rats

Reply 1228

datpr0

2

Original post by RhyaCeri

there was one on a colony of rats

Eh, vermin... bacteria... same difference.

Kappa

Reply 1229

CD223

OP

10

Differential equation is the rate of forum posts on TSR is inversely proportional to time after the exam.

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Reply 1230

datpr0

2

Original post by saeed97

u wunt sum? i'll giv it 2 u

gr8 b8 m8 I r8 8/8

Reply 1231

Plasmapause

12

Excuse me, but can one of you explain how to do question 7 on this paper?
I know what the answer is, but I don't know how to get there.

Reply 1232

Ual12

6

Do we get any marks if we made one or two slips, like signs ?? Because its so easy to make silly mistakes in C4 :frown:

How many method marks can we get max???

Reply 1233

2014_GCSE

3

Original post by Plasmapause

Excuse me, but can one of you explain how to do question 7 on this paper?
I know what the answer is, but I don't know how to get there.

Excellent description from datpr0 earlier in the thread:

Basically it's modelling the change in height of the tide over a period of time (i.e. rate of change of the height of the tide) as a cosine graph, whereby the maximum and minimum values for this are 1.3 and -1.3 (dh/dt = +/- 1.3).

From the question you know: dh/dt = acos(kt).

From a cosine graph you know that the maximum and minimum points occur at 1 and -1 respectively (i.e. cos = 1 or -1). Therefore a = 1.3 or -1.3. You can consider this as a stretch parallel to the y-axis of SF 1.3 if you like.

k is adjacent to the t in the model and t is being measured on the x-axis. You know the period of a cosine graph is 2pi and the tides occur every 12 hours (i.e. t = 12). This means that k becomes 2pi/12 in order to cancel with the 12 introduced through t so that you end up with cos(2pi) not cos(12).

Reply 1234

gloria0816

1

I know this may sound stupid but how do you integrate this quickly ImageUploadedByStudent Room1433791146.300579.jpg

Thanks

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Reply 1235

Plasmapause

12

Original post by 2014_GCSE

Excellent description from datpr0 earlier in the thread:

Basically it's modelling the change in height of the tide over a period of time (i.e. rate of change of the height of the tide) as a cosine graph, whereby the maximum and minimum values for this are 1.3 and -1.3 (dh/dt = +/- 1.3).

From the question you know: dh/dt = acos(kt).

From a cosine graph you know that the maximum and minimum points occur at 1 and -1 respectively (i.e. cos = 1 or -1). Therefore a = 1.3 or -1.3. You can consider this as a stretch parallel to the y-axis of SF 1.3 if you like.

k is adjacent to the t in the model and t is being measured on the x-axis. You know the period of a cosine graph is 2pi and the tides occur every 12 hours (i.e. t = 12). This means that k becomes 2pi/12 in order to cancel with the 12 introduced through t so that you end up with cos(2pi) not cos(12).