The Edexcel M2 (31/05/12 - AM) Revision Thread

Original post by Jorgeyy

I haven't looked at it but the fact 106 + 74 = 180 jumps out at me :wink:

Thanks it makes everything clear, captain obvious! I noticed it myself, but according to the problem the angle should be 74 and not 106, and i don't understand why 106, it looks like they written it down randomly.

Reply 185

Mathematix

2

Original post by soempty

Thanks it makes everything clear, captain obvious! I noticed it myself, but according to the problem the angle should be 74 and not 106, and i don't understand why 106, it looks like they written it down randomly.

umad?

Reply 186

Original post by soempty

Thanks it makes everything clear, captain obvious! I noticed it myself, but according to the problem the angle should be 74 and not 106, and i don't understand why 106, it looks like they written it down randomly.

Make sure you got the vector right, -2.5i - 5 sqrt3 j and then draw the vector itself. Then because you have to work out the angle with respect to the "i" vector (which is always towards the right; positive x axis) it would be 180 - 74.

If you still dont get it, draw a "CAST" graph from C2, that may help or confuse you more... Sorry xD

Original post by Jorgeyy

umad?

^LOL

(edited 11 years ago)

Reply 187

oli_G

12

Original post by Serpentine111

This is so bad :s-smilie:

Not even finished revising yet, nevermind starting past papers :frown:

I really hate this chapter! Our 'teacher' has barely taught us any of it and I didn't even know we were expected to know C3

Can anyone explain why (ucosθ*2usinθ)/9.8 is equal to u^2sin2θ/g please? (This is a show question, and u^2sin2θ/g is the answer you are supposed to get)

Would I just be ok to show that it is equal to each other without any working?

I'm in the same boat and I saw a question yesterday where you had to show an equation to be true.

Luckily on the mark scheme it was sufficient to just say that it equaled the final expression (lets just hope if any c3 trig comes up it's in a show that question :tongue:

)

Reply 188

Groat

13

Reminder to anyone doing lamina questions - if you use the table method and a shape is cut out, don't forget to subtract the moments, not add!

Reply 189

Original post by Groat

Reminder to anyone doing lamina questions - if you use the table method and a shape is cut out, don't forget to subtract the moments, not add!

xD Did you slip up on a lamina question :dance:

By the way have you got the Jan 2012 Question paper? I think I only ever did the first 3 questions of it and got bored and cant find my printed copy :unimpressed:

EDIT On second thoughts, Its ok I found it :P

(edited 11 years ago)

Reply 190

Original post by dzone25

Make sure you got the vector right, -2.5i - 5 sqrt3 j and then draw the vector itself. Then because you have to work out the angle with respect to the "i" vector (which is always towards the right; positive x axis) it would be 180 - 74.

If you still dont get it, draw a "CAST" graph from C2, that may help or confuse you more... Sorry xD

+_+
But if i draw a picture it clearly shows that angle is 74...
I think if i get such question in exam, i will write exactly opposite of my answer to get it right.

Reply 191

Original post by soempty

+_+
But if i draw a picture it clearly shows that angle is 74...
I think if i get such question in exam, i will write exactly opposite of my answer to get it right.

Oh i see why. Impulse in i direction would be negative... Argh! I feel the shame.

Reply 192

Original post by soempty

Oh i see why. Impulse in i direction would be negative... Argh! I feel the shame.

Yep, Impulse is in negative x direction and negative y so on a graph that would be the bottom left square. Since the "i" is the same as the positive x axis it means its 180 -74

;J

Reply 193

GnomeyD

can anyone help me with jan 2010 question 7b)? instead of getting 6 / ( 4 + (20/ 16 + 3π), as it says on the mark scheme, I have it the other way around. i feel like i'm missing something really obvious!

Reply 194

Original post by dzone25

Yep, Impulse is in negative x direction and negative y so on a graph that would be the bottom left square. Since the "i" is the same as the positive x axis it means its 180 -74

;J

WUT? No way it is negative in y direction, if I=mv-mu it would be I=0.25x40xCos30 - 0.

Reply 195

Original post by GnomeyD

can anyone help me with jan 2010 question 7b)? instead of getting 6 / ( 4 + (20/ 16 + 3π), as it says on the mark scheme, I have it the other way around. i feel like i'm missing something really obvious!

"PQ makes with the horizontal..." did that help :P

Reply 196

geditor