Edexcel M2/M3 June 6th/10th 2013

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Hey I got the same but instead of simplifying it I just left it as x=-3/4√3ag/5 the minors because it is going left, but I think we need to add the horizontal distance from O when the string was slack?? Same for the y??

Posted from TSR Mobile

No you don't have to add the distance from initial position or anything. It is all relative to origin.
I am saying this 3rd time but using vectors just scraps off all these :P once you take the i as positive x-axis and j as positive y-axis, and then find your initial velocity and position vector nice and clear with correct signs (directions) you have nothing else to worry about.

Reply 721

milliezhao

And SHM I got w is √50, a is 0.2, time in the end was 0.296?

Posted from TSR Mobile

Reply 722

Alexn159

Original post by milliezhao

And SHM I got w is √50, a is 0.2, time in the end was 0.296?

Posted from TSR Mobile

Yeah I got that

Also 2 posts above, what do you mean by COM question?

Reply 723

thephysicsguy

Original post by milliezhao

For Com question part a I got 5.1 and b I think it was 1.72 or something, anyone got the same?

Posted from TSR Mobile

They don't sound familiar to me, do you remember the fractions. They were really big but I still preferred to leave them exact. Btw I spent at least 20 mins checking this question :P

Reply 724

thephysicsguy

Original post by Alexn159

Yeah I got that

Also 2 posts above, what do you mean by COM question?

He means centre of mass.
I got the same for SHM!

Reply 725

Joshmeid

Original post by study beats

guys i failed this exam really badly, i am crying, how can i get over this...my life is ruined

I'm sure you did better than you think you did.

Reply 726

Serpentine111

Original post by milliezhao

For Com question part a I got 5.1 and b I think it was 1.72 or something, anyone got the same?

Posted from TSR Mobile

Wasn't part a between 0 and 2? :s-smilie:

Reply 727

rath90

Original post by Xiroz

For those x and y equations, did you remember that they do not start at the origin? initial x position is -4a/5 and initial y is 3a/5

How many marks do you think I will lose for not putting the initial position?

Reply 728

Alexn159

I got 1.31 on the graph.
Then 1.77 from the base on solid
Sound familiar to anyone?

and how many marks do you think I will lose on the last question for putting -gt^2 rather than -1/2gt^2 because I took away an extra -at^2 by using a wrong equation right at the end

(edited 10 years ago)

Reply 729

thephysicsguy

Original post by Serpentine111

Wasn't part a between 0 and 2? :s-smilie:

Exactly!
I think very very roughly I got something close to 1.5.
For second part don't forget to subtract your answer from 2a, i got something like 1.3 maybe...

Reply 730

thephysicsguy

I just remembered the whole centre of mass question and I am quiet sure about it. I will appreciate if you can double check it for me.

http://i40.tinypic.com/2z6eezt.jpg

(I was about to do the proving part aswell but I passed that to just get the answer using the formula)

(edited 10 years ago)

Reply 731

study beats

Original post by miketree

Should have studied instead of listening to music on your beats.

i did study, and what beats?

Reply 732

study beats

Original post by Joshmeid

I'm sure you did better than you think you did.

i really didnt

Reply 733

idknow

The paper was simple, i made a stupid mistake as i always do... im expecting to lose maybe 8 - 6 marks all due to subbing 0 into (x+1)^5/5 and getting 0 -.- pretty annoyed but par that it was ok. As for the rest of the answers:
mu:0.179
Force question: 2t^2+t=v v=6 x=27/8m
string question:0.805 (velocity) not sure though, 0.383m travelled
SHM: show that, root50 and time was 0.296
COM... 1.51, 0.721 (i got 1.5 and 0.729 close or what)
Circle... x=vt-a3/5 y=vt-gt^2/2+ a4/5 (may have got the 4/5 and 3/5 mixed up though) i think the velocity was root3ag/5

please correct me if i am wrong and possibly maybe if anyone can figure how many marks would i lose for that stupid COM i used all the right methods for both parts, i integrated right but my only fault was the mistake with subbing my values, it annoyingly affected my mass as well got 243/5 instead of 242/5 do you think i can get 4 marks on the first part and 3 on the next part?

(edited 10 years ago)

Reply 734

bbcs2k9

Original post by VSEPR

Also someone had scribbled all over the C3 formulae in the booklet when I tried to check the equation for volume of revolution; it wasn't there and I wonder if some poor soul will get into trouble when they do C3 on Thursday...

Revolution is in C4

Reply 735

milliezhao

Original post by idknow

I got exactly the same except question except question 7 where I forgot the add the initial position :frown:

how many marks do you think I will lose? I think for the com question you won't lose more than 3 marks

Posted from TSR Mobile

(edited 10 years ago)

Reply 736

bbcs2k9

Original post by milliezhao

For Com question part a I got 5.1 and b I think it was 1.72 or something, anyone got the same?

Posted from TSR Mobile

That cant be right because the length of it was only 2, I got approximately 1.5 if that's what you mean.

Reply 737

cupcake_51

study beats,

Dw I'm sure it wasn't terrible . Ya never know about the boundaries. Just ignore him, doesn't seem to be the nicest of people :P.

Posted from TSR Mobile

(edited 10 years ago)

Reply 738

milliezhao

Original post by bbcs2k9

That cant be right because the length of it was only 2, I got approximately 1.5 if that's what you mean.

Sorry, I meant 0.51 and 0.7, I was tired :s

Posted from TSR Mobile

Reply 739

idknow

Original post by milliezhao

F

I got exactly the same except question except question 7 where I forgot the add the initial position :frown:

how many marks do you think I will lose? I think for the com question you won't lose more than 3 marks

Posted from TSR Mobile

3marks???? i would be really happy but im very sceptical, as for how many you would lose probably 2 accuracy for each answer maybe and if they really aren't lenient a mark for the method so max u should only lose out on 3 but probably 2