[stunnaman]

(Original post by teachercol)
as i said

guess I just have to live on hope. hated that A0 questions i used the right forumula and i said the osicllation of sand grane shud be in phase with osciallation of metal plate (also said it shud follow a smh ).
then i used the sam forumula but i didnt put 9.81 for accelaraton becuz stupid me had to try find the acceleration using the forumula. would i get any marks?

[teachercol]

You may get some credit - but how much I just dont know. It comes down to exactly what you wrote and whether it hits any marks on the mark scheme.

[SJS101]

Teachercol, i know you have said that we have to wait for the grade boundaries but based on previous years grade boundaries do you think i will get an A*? Your opinion will be very much appreciated.

I got 39/40 on the coursework
Think i got 90/100 on G485
Think i got 52/60 on G484


tHANKSSS

[teachercol]

IF you indeed get those marks then you shoudl get an A*.

But as I've written before

you may not get 59/60 for your coursework. All marks are moderated. Some centres get pulled down a lot. Trust me. But some dont.

90/100 on G485 will always score very highly and be close to 150 UMS.

52/60 ? Dont know.

Many of my students in Jan - and there are some pretty good ones - thought they'd only dropped 7/8 marks - but ended up with B's . The grade boundaries were brutal and the marking was nit-picking.

Most students dont realise how tough the marking is. If its isnt exaclty right, it doesnt get the mark is the norm. if they cant quite read it, they wont. If it can be interprested wrongly, they do. The exact wording counts.

[SJS101]

(Original post by teachercol)
IF you indeed get those marks then you shoudl get an A*.

But as I've written before

you may not get 59/60 for your coursework. All marks are moderated. Some centres get pulled down a lot. Trust me. But some dont.

90/100 on G485 will always score very highly and be close to 150 UMS.

52/60 ? Dont know.

Many of my students in Jan - and there are some pretty good ones - thought they'd only dropped 7/8 marks - but ended up with B's . The grade boundaries were brutal and the marking was nit-picking.

Most students dont realise how tough the marking is. If its isnt exaclty right, it doesnt get the mark is the norm. if they cant quite read it, they wont. If it can be interprested wrongly, they do. The exact wording counts.

I appreciate that, as i did the Newtonian World exam in Jan aswell.

I got 48/60 raw marks and that was because they were nit-picking indeed.

Internal energy - i wrote in the system instead of in the atoms/molecules... did not get the mark

Pressure - I did not have the world MANY before collisions... did not get the mark

Pressure - I wrote momentum of the molecule after colliding with the wall is -2mv... did not get the mark (NBOD)

and lots moreeee :/

Also by giving myself 52/60 was being extremelly picky, there is no way i got under 51 for example.

Anywayz thanks

[teachercol]

Thanks for your comments. I got about a dozen of my students papers back and went through them. Their experience was much like yours - several didnt write many and didnt get the mark.

There was v little if any BOD.

[Small123]

Reckon I got 51/60 minimum - any rough ideas on that UMS? I'm well aware it's nothing other than speculation

[Holby_fanatic]

Around 50/60 marks according to your mark scheme! Much improved from the U in January I think!

Thank you for posting your mark scheme, Teachercol. It is much appreciated.

[Mathlete 4 the win]

I still can't believe I plotted F against v^2 wrong. I seem to have got the more challenging questions right and then just spooned all the easier ones. The swines

[ash356]

(Original post by teachercol)

Q1 a) Accelerates in direction of net force/ changes velocity / changes momentum (1)
b) i) Impulse = change in momentum (1)
ii) Area under graph = impulse = change in momentum = mvf - mvi
vi = 0 so vf = area / m (2)
c) i) Mean force = change in momentum per unti time
= mvf/t = 0.058 x 52/4.2E-3 = 7.18E2 N (2)
ii) If momentum is conserved
change in momentum of racket = - change in momentum of ball
m(38-32) = 0.058 x 52 so m = 0.50 kg (2)

I did it totally different
I couldn't manage it using that method for some reason, so I stated Newtons third law (Stuck it in the extra space at the end), calculated how much the velocity changed in the time period given to get acceleration, and then used F=Ma to find the mass. Used the force as equal to the one given in ci due to the aforementioned third law.
Radically different method, which makes me think I did it totally wrong, but I still got 0.5kg

[teachercol]

Comes to the same thing. (thats where the conservation of momentum comes from!)

[ash356]

(Original post by teachercol)
Comes to the same thing. (thats where the conservation of momentum comes from!)

Oh, thank heavens for that! :P
Thought I was waffling on about something totally irrelevant when doing it
Thanks!

[Namod]

(Original post by teachercol)

Q4 a) i) Shc = energy needed to raise temp of unit mass of substance by unit temp
(note they stopped marking 1kg and 1K correct last year)
ii) Fusion - heat needed to convert solid to liquid at melting point
Vaporisation - heat needed to convert liquid to gas at boiling point (1)
b) i) A to B KE increasing because temp is increasing
(+ some small Increae in PE because most substabces expand when heated)
B to C Temp is constant so Ke constant
PE increases as bonds melt + substabce melts (2)
ii) 4 x smaller since it takes 4 x less time for same increase in temp
ie same temp rise needs 4x less energy (2)
C) i) P = W/t = m/t x c x dT = (3.6E-3)/60 x 1000 x 4200 x (36.7-17.4)
= 4.86kW which is approx 5kW (4)
ii) Usual stuff - some heat lost to surrounding / heats up pipes etc
so P will need to be higher than calculated. (2)
Total 12

if some heat is lost than energy will be less so power will be less?

[teachercol]

Actually the question asks about RELIABILITY not accuracy so my answer here wasnt right.

The examiners expect you to write about why if you did the experiment again you might not ge the same answers.

eg - water pressure might change so that the flow rate changes.

[saltnpepper]

Thanks for putting the effort to make this MS
Just a few mistakes I spotted. Never define impulse as the change in momentum, they don't accept it. You're expected to recall that it is the change in momentum. The definition is the 'Force x time in which the force acts/duration of collision'.
4)a)i) is right, but they also accept c=Q/m x (delta t), with all symbols defined.
Am I allowed to upload the MS? I have it but I haven't got the paper. Anyone got the paper?

[saltnpepper]

Actually, I found the paper, someone uploaded it:
https://skydrive.live.com/?cid=518db...F043877A%21199
MS:

[teachercol]

(Original post by saltnpepper)
Thanks for putting the effort to make this MS
Just a few mistakes I spotted. Never define impulse as the change in momentum, they don't accept it. You're expected to recall that it is the change in momentum. The definition is the 'Force x time in which the force acts/duration of collision'.
4)a)i) is right, but they also accept c=Q/m x (delta t), with all symbols defined.
Am I allowed to upload the MS? I have it but I haven't got the paper. Anyone got the paper?

Quite right - they used to accept change of momentum for impulse - they dont any more.

You can use equation to define shc no prob.

Its Ok to upload mark scheme and paper now.

[Davidbazzy]

Anybody have the grade boundaries for this paper?

[ginister]

When do you use pv=nrt and when pv=nkt?

[RobW1995]

is there any plans to make an unofficial mark scheme for Newtonian world 16/1/13? if so when will it be up?