M3 Pre-Exam thread (edexcel)

Reply 320

Trollolollol

2

Original post by Cairo133

Honestly one of the worst papers I have ever done... I doubt I even got half marks :frown:

Agreed

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Reply 321

MAD Phil

Original post by lse2912

can anyone post a mark scheme for this please?

Here's my first attempt. Let me know about my mistakes, please - like for the M4 paper!

M3 201206 MAD Phil.pdf323.3KB

Reply 322

Trollolollol

2

I love you (no homo) <3

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Reply 323

Trollolollol

2

And **** I managed half marks Ish

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Reply 324

David.holt123

Original post by ihatethispart

This is my worked solution for 6b) Can anyone confirm whether or not this matches the answer on the paper?

Hey, I did exactly the same as you, but didn't have time for the last two lines. Any idea of how many marks I should get for it?

Also, on Q1b, I got to the stage of finding t in terms of x, but didn't read the question properly and left it like that. How many marks would you say for that?

Completely forgot how to do Q6a and missed out the question where you had to find k, which was the mass of the particle attached to the solid!

Really worried about the scaling of this one.. :/

Thanks in advance :smile:

Reply 325

Antimony

Original post by MAD Phil

Here's my first attempt. Let me know about my mistakes, please - like for the M4 paper!

Thanks!

In your Q3, I don't understand why you can't give 223.5N because on the first page of exam paper they say take g as 9.8

I got the same answers except for Q3 where I put 223.5N and I couldn't do part b of 6 :/

(edited 11 years ago)

Reply 326

Trollolollol

2

Yeh I used g as 9.8 it's fine

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Reply 327

Kaiser7

6

If I had 10-15 more minutes I probably would have done the tension question (number 3) and number 6. In number 3, I got the idea and did the resolution correctly but went wrong algebraically, so I got different final answers. I did 6a using a vertical strip not a horizontal one; it kept ending up as 4root3/3 a, so I left it as that :/ I was actually just starting to do 6B and I completely knew how to do it, but time was up. :frown:

I also left 4B blank, and got 7D incorrect.

Edit: Just realised I also got the circular motion question pretty wrong as well. Proved what they wanted but not as the mark scheme above did it, so I'm pretty sure my proof was invalid. I don't remember my answer for the second part (maximum speed) but I think I did it as R acting towards the center not away from it so yeah, I think I messed that up too.

What do you guys roughly think I can get?

(edited 11 years ago)

Reply 328

TFS

For question 6a, I integrated y=root3*x (the equation of the line of one half of the triangle) from 0 to a to work out height of centre of mass from base then said by symmetry this would be the same for full shape and so centre of mass from the top is root3 minus that answer which comes out correctly. Can anyone confirm that's okay?

Reply 329

ihatethispart

Original post by David.holt123

Hey, I did exactly the same as you, but didn't have time for the last two lines. Any idea of how many marks I should get for it?

Also, on Q1b, I got to the stage of finding t in terms of x, but didn't read the question properly and left it like that. How many marks would you say for that?

Completely forgot how to do Q6a and missed out the question where you had to find k, which was the mass of the particle attached to the solid!

Really worried about the scaling of this one.. :/

Thanks in advance :smile:

I actually don't know how the marks will be rewarded myself. I assume some marks would be rewarded for calculating the correct centre of mass and are of the triangle and the sectors so maybe 3-4 marks for an incomplete answer?

On 1b) If you found the constant, then rearranging to get x in terms of t would be a mark and then a final accuracy mark? So maybe 4 out of 6?

I think a lot of people like myself freaked out yesterday because the questions felt so weird, I mean, only FM candidates do M3 and still most people here say it's hard. I'm hoping that my generous self-mark of 57 would at least get me 70UMS.

And here's the solution to 6a? just in case you're interested:

(edited 11 years ago)

Original post by MAD Phil

Here's my first attempt. Let me know about my mistakes, please - like for the M4 paper!

if you look at past exam papers when ever you have to give an answer (even if you have used (g=9.8) they say accept answer 1.23 or better.... they dont tend to worry about being over accurate as we are not sad anal physicists! sorry pete

Reply 331

MAD Phil

Original post by Antimony

Thanks!

In your Q3, I don't understand why you can't give 223.5N because on the first page of exam paper they say take g as 9.8

I got the same answers except for Q3 where I put 223.5N and I couldn't do part b of 6 :/

I agree with your argument completely, but I seem to remember at least some markschemes saying to take off one mark if you give 4 or more sig figs when you have used g = 9.8.

Sorry, I don't have time to find a reference right now - I'm trying to submit some comments on the planning of Brighton station approach before the consultation finishes tonight! (Vote for option 1B, by the way!)

Reply 332

natninja

21

Original post by MAD Phil

Here's my first attempt. Let me know about my mistakes, please - like for the M4 paper!

thanks

for the last part of the last question I got a different answer :/ and I doubt they'd remove a mark for the unjustified accuracy in 223.5 because otherwise your other answer makes no sense and it's still 1dp :smile:

reckon I probs got about 56/75 which would be the worst paper I've done

Reply 333

MAD Phil

Original post by physics1

if you look at past exam papers when ever you have to give an answer (even if you have used (g=9.8) they say accept answer 1.23 or better.... they dont tend to worry about being over accurate as we are not sad anal physicists! sorry pete

I hope you're right!

Reply 334

natninja

21

Original post by ihatethispart

I actually don't know how the marks will be rewarded myself. I assume some marks would be rewarded for calculating the correct centre of mass and are of the triangle and the sectors so maybe 3-4 marks for an incomplete answer?

On 1b) If you found the constant, then rearranging to get x in terms of t would be a mark and then a final accuracy mark? So maybe 4 out of 6?

I think a lot of people like myself freaked out yesterday because the questions felt so weird, I mean, only FM candidates do M3 and still most people here say it's hard. I'm hoping that my generous self-mark of 57 would at least get me 70UMS.

And here's the solution to 6a? just in case you're interested:

I spoke to my teacher about doing that and he reckons just the last accuracy mark.... dw, usually 57 is more than 70 UMS :smile:

once 57 was 99UMS I think (2009)

Reply 335

rugby274

i have a few questions that are realy annoying me, can someone help?

1) for the weird triangle question with sectors cut out, do you get any marks if you find the com using medians in a triangle instead of calculus? (i paniced)

2) what do people think the grade boundaires are? (it was the worst paper i've ever done)

3) what do you reckonthe raw mark for 89 ums would be as that is what i need for the A*

Reply 336

ihatethispart

Original post by natninja

I spoke to my teacher about doing that and he reckons just the last accuracy mark.... dw, usually 57 is more than 70 UMS :smile:

once 57 was 99UMS I think (2009)

How many marks do you think I'd lose for not finding the constant in 1b) I did the question while the invigilators were collecting people's papers. I wrote c=0, x=ln(2t)

Reply 337

natninja

21

Original post by ihatethispart

How many marks do you think I'd lose for not finding the constant in 1b) I did the question while the invigilators were collecting people's papers. I wrote c=0, x=ln(2t)

you'd lose the final accuracy mark and probably 2 method marks, possibly one more accuracy mark :/ hope you managed the COM qs ok... I didn't :P

Reply 338

Trollolollol

2

Original post by rugby274

i have a few questions that are realy annoying me, can someone help?

1) for the weird triangle question with sectors cut out, do you get any marks if you find the com using medians in a triangle instead of calculus? (i paniced)

2) what do people think the grade boundaires are? (it was the worst paper i've ever done)

3) what do you reckonthe raw mark for 89 ums would be as that is what i need for the A*

1) na it will under do not accept on MS as it asked for calculus.

2) <70 for full UMS

3) hence <65 for 90.

How much depends how lucky we get. Obv if 60 for full, 54 for 89 ish

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