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Edexcel m1 official thread ( May 13 Monday 2013)

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Okay can someone just clarify this for me please, I'm having a dumb moment..

When something is due north/south, you equate the i components and when something is due west/east you equate the j components?

Funnily enough I'm cool with NE/SW but I'm just having a blank right now.. Exam nerves I guess lol

Thanks guys

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Yup!

Original post by posthumus

I am seriously confused :confused:

Sometimes they simplify the velocity, so I have:
15i-5j for the velocity

so for my equation "s" I did:

s=(-2i -4j) + t(15i-5j)
s=i(-2+15t) + j(-4-5t)

But they got

s=i(-2+9t) + j(-4-3t)

What on earth???? :confused:

Same ratio 9/3 = 3... 15/5 = 3... but doesn't that make a significant difference ! :frown:

Thanks in advance for any replies

Could you post the question, please? :smile:

Original post by SoapInMyEyes

What do you do when something is due NE, NW, SW, SE! for Vectors.

It's easier to explain if you post an example of a question. :smile:

Original post by Frankster

Hey does it matter if you write your vectors in column form or do you have to write it in i j form? I mean obviously if the question states that show. ..... (in i j form).... then yes I'll write it in i j form, but otherwise?

Thanks :smile:

No, it does not in most cases. :smile:

Original post by Frankster

Also what are the guidelines in terms of the accuracy to which you should state your answer in? It's sooooo confusing what with S1 coming up too!! Thanks :biggrin:

For M1, write your answer to 2 or 3 significant figures unless otherwise specified. :smile:

Reply 401

posthumus

Could someone confirm that they are wrong :smile:

I'm stuck on part c) I believe P at t=5 has (-10i + 2j)... I end up with 11.3 as my answer (from the i vector) ... But they have something totally different -_- I think they also did tan= A/O instead of tan=O/A

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Reply 402

posthumus

Original post by usycool1

Could you post the question, please? :smile:

I think I found my mistake :colondollar:

I made t=0.4 instead of 40/60... so I guess you can't simplify the velocity as that would change the magnitude, I think I'm getting mixed up between vectors in C4 with M1 :tongue:

Reply 403

posthumus

Original post by posthumus

Could someone confirm that they are wrong :smile:

Forgot to post the image :colondollar:

ImageUploadedByStudent Room1368434895.736275.jpg

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Reply 404

Rhodopsin94

Original post by posthumus

Forgot to post the image :colondollar:

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You always take i to be to the right, therefore you worked out the angle with i, but in the wrong direction (as annoying and confusing as that might sound.

Using Z angles you can see that the other angle of your triangle (other than 90) is equal to the angle between the velocity direction and a vertical line directly up from where you have taken your angle. Then to get to i in the direction of right, you need to add 90 degrees.

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Reply 405

RoyalBlue7

Original post by Satta101

Does anyone know if you'll get marks for using two methods but one of them has the correct answer and the other has the wrong answer?

Original post by outsider95

You'd lose all your marks. Cross out any incorrect working, and if you're stuck between two answers, pick one and cross the others out, examiners aren't going to credit you for a correct solution if you've shown that you're not confident in your answer. It's like me saying the square root of 25 is 5 or 6, the examiner would mark that as incorrect, you're only allowed one chance to get it right

Oh no...you'll get full marks!

Look at the Jan 2013 marking scheme sixth point under general instructions for marking
This applies to all Maths GCE papers as the marking scheme for M1 Jan 2013 shows.

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(edited 10 years ago)

Reply 406

Frankster

Anyone got their M1 book on them? Page 167 question 6 about particle sliding down a rough plane at an angle to the horizontal? I got 0.44 for acceleration and 2.55 for reaction force?

Reply 407

JenniS

on the exam style paper in the textbook, question 5, why do you not inculde the mass of the object when resolving vertically?

Reply 408

QUANTAM

Good luck brothers and sisters. My stress is so much though that it's magnitude can be resolved using pytag. :frown:

Reply 409

lebron_23

Just quickly guys, if i could direct your attention to the last part of question 5 on june 2002. I'm stumped. If someone could explain how they would go about working it out I would be eternally grateful :biggrin:

Thanks in advance

Also, if you haven't got the paper handy, just ask and I'll post a picture

Good Luck!!

Original post by lebron_23

Thanks in advance

Also, if you haven't got the paper handy, just ask and I'll post a picture

Post A pic

Reply 412

lebron_23

Original post by JenniS

on the exam style paper in the textbook, question 5, why do you not inculde the mass of the object when resolving vertically?

It's because you're simply looking at forces there. It wants the resultant force and so when you think of forces and resultants and all that good stuff, you need not take into account the mass. It comes into play in the second part of the question though.

Reply 413

KalSA

I really hope they don't end up giving us a ridiculous vectors question - just can't seem to get the hang of it :frown:

Really shaking in my boots.... except I'm not exactly wearing boots.

Reply 414

usycool1

Original post by Frankster

Anyone got their M1 book on them? Page 167 question 6 about particle sliding down a rough plane at an angle to the horizontal? I got 0.44 for acceleration and 2.55 for reaction force?

I'm getting 0.33ms^-2 for the acceleration but I agree with 2.55N for the normal reaction. :yy:

Reply 415

lebron_23

Original post by Mad_Study

Post A pic

Its the last part, thanks.

Screen shot 2013-05-13 at 10.06.44.png27.9KB

Reply 416

Frankster

Original post by usycool1

I'm getting 0.33ms^-2 for the acceleration but I agree with 2.55N for the normal reaction. :yy:

Could you tell me how you got 1/3 ms^-2 for the acceleration? :confused:

really stumped. Thanks :smile:

Also in vectors when something is north-east, south-east, north-west, south-west, to another object how do you go about those questions? I can do the ones which are due south or north :colondollar:

Reply 417