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

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Thanks! Yeah I was ecstatic. Was quite funny how the harder exams last year were C2 and M1 which I got 100 UMS on, but the easier one (C1) I got 97 in...

In the way of tips, Id say be confident with your modelling assumptions, and know some basic trig to quickly resolve forces into components. Trig identities like sinx/cosx=tanx can also sometimes arise. Approach the paper having done all the past papers (as many as you can find) if possible.

Guys I've found out online how to do the question ill post the link...

http://en.allexperts.com/q/Calculus-2063/2013/1/modelling-differential-equations.htm involved multiplying by 99/99 :eek:

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Reply 81

madmenace

Original post by CD223

It's a horrid question! I can't seem to do it for the life of me!

When they apply the horizontal force X, at first they are resolving perpendicular to (at right angles to) the slope. See my modified drawing below. Do you see that the angle I've drawn is 30 degrees?

If you look at the fact that the object is in equilibrium in the plane perpendicular to the slope, R must equal Xsin30 added to the component of the weight which acts perpendicular to the slope (40gcos30) :smile:

ImageUploadedByStudent Room1426455608.784691.jpg

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Hi thanks for taking the time to draw the image and everything I understand why the angle is 30degrees, (same as slope and horizontal base) but when you split up X into vertical and horizontal why does it not act vertically downwards like the weight(and is perpendicular to slope) that's what I saw trying to do and therefore I couldn't say Xsin30 beacuse x wasn't the hypotenuse and force up the slope was

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Reply 82

saad97

Original post by CD223

Wow! You must be predicted an A* in maths then! *Jealous* :tongue:

Getting 100 UMS on C2 last year was amazing! That paper was such a bastard, I swear I missed half the questions out -.-
But yeah I've only done 1 paper so far and it went well.
To be honest the topic I find the most difficult is probably projectiles. The rest I'm good with.

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Reply 83

madmenace

Original post by CD223

Yes I did

I can try and help! I'm doing M2 this year so I guess it might help me too haha.

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Yep, I think the correct way of drawing it is the bottom with the arrow on the right perpendicular to the plane but it's just I don't understand why the top diagram is wrong with the arrow vertically downwarss :frown:

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1426457623997.jpg35.7KB

Reply 84

CD223

Original post by madmenace

Guys I've found out online how to do the question ill post the link...

http://en.allexperts.com/q/Calculus-2063/2013/1/modelling-differential-equations.htm involved multiplying by 99/99 :eek:

Oh that is so close to what we had it's infuriating! Thanks for finding it!

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Reply 85

CD223

Original post by madmenace

Excuse the poor drawing. Does this help? Think about if you tilted the horizontal and vertical to the slope axis by 30 degrees...like this:

ImageUploadedByStudent Room1426459214.525116.jpg

ImageUploadedByStudent Room1426459214.525116.jpg

Excuse the poor drawing.

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Reply 86

CD223

Original post by saad97

Wow! You must be predicted an A* in maths then! *Jealous* :tongue:

I am predicted an A* yeah :smile:

I really want one but they're making the papers harder!!

C2 was horrid last year. God knows how I managed that. Must have ate something right for breakfast!

Projectiles are difficult because there's so much you can be asked about. Just stick at it and you'll be okay! :tongue:

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Reply 87

CD223

Original post by madmenace

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Does my diagram (albeit poorly constructed) make sense now? :s-smilie:

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Reply 88

saad97

Original post by CD223

Oh that is so close to what we had it's infuriating! Thanks for finding it!

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I don't understand how they "solved for x"? :/
By the way thanks for the link! :smile:

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Reply 89

CD223

Original post by saad97

I don't understand how they "solved for x"? :/
By the way thanks for the link! :smile:

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They used the same method we did by multiplying through by 1-x and expanding.

They raised by e earlier and called e^C a constant K. It seemed to be a neater solution aha.

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Reply 90

madmenace

Original post by saad97

I don't understand how they "solved for x"? :/
By the way thanks for the link! :smile:

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Expand brackets, rearrange and factorise

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Reply 91

CD223

Original post by madmenace

Expand brackets, rearrange and factorise

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To be fair I think most of the marks we would have got. Just the answer mark missing. Maybe 4 out 6?

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Reply 92

madmenace

Original post by CD223

Excuse the poor drawing. Does this help? Think about if you tilted the horizontal and vertical to the slope axis by 30 degrees...like this:

ImageUploadedByStudent Room1426459214.525116.jpg

Excuse the poor drawing.

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WooaaH didn't know you could look at it like that yeah I understand thanks!!!
It was just I was drawing the vector triangle all wrong... X beacones parallel to slope and 90degrees to slope not not at 90degrees to X

The pic I posted earlier shows the mistake I was making

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(edited 9 years ago)

Reply 93

saad97

Original post by CD223

To be fair I think most of the marks we would have got. Just the answer mark missing. Maybe 4 out 6?

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Hmm yeah most likely, we just missed the final step I guess.
Thanks for all the help guys, much appreciated! :smile:

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Reply 94

saad97

Original post by CD223

I am predicted an A* yeah :smile:

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I know, there were some right horrible papers last year from AQA! :frown:

But anyway good luck, I hope you get your A*, I'm sure you will! :biggrin:

Haha naa you're just really clever and seem like you put the hours in, you deserved it. :smile:

I know and splitting it up into horizontal and vertical components can get confusing at times if you don't set your work out correctly and know what's what.

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Reply 95

CD223

Original post by madmenace

That makes perfect sense. Don't worry! It's not like I got that first time in the exam either! I remember redoing the whole question after making the same mistake haha!

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Reply 96

CD223

Original post by saad97

Hmm yeah most likely, we just missed the final step I guess.
Thanks for all the help guys, much appreciated! :smile:

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Don't feel I helped much given I only got as far as you did anyway 😂😂😂

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Reply 97

CD223

Original post by saad97

I know, there were some right horrible papers last year from AQA! :frown:

But anyway good luck, I hope you get your A*, I'm sure you will! :biggrin:

Haha naa you're just really clever and seem like you put the hours in, you deserved it. :smile:

I know and splitting it up into horizontal and vertical components can get confusing at times if you don't set your work out correctly and know what's what.

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I hope it's not an indication of how hard this year is...

I do hope so. It's my only subject I'm desperate for one in! My offer is AAA so I don't exactly need one but after the work I've put in I feel like I might as well aim for one!

Ah, well thank you for the compliments but I'm definitely not clever if you see me on a bad day. I make all sorts of mistakes :wink: