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PAT Solutions.

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Reply 380
Original post by samkanwoods
I get 700seconds and 23C. How did you get 49s. I used E=mc(delta)T. The frying pan receives 70 Joules per second and I worked out E=2*490*(70-20)=49000J. Therefore Time=49000/70=700s.


Oh dear, I messed up and calculated it as though the area of the pan was 1m^2, not 0.07m^2. Redid it and got 700s :smile:
For question 17 on the 2010 paper, what is meant by the 'line of intersection of the two mirrors'?
Reply 382
Original post by cameron95
For question 17 on the 2010 paper, what is meant by the 'line of intersection of the two mirrors'?


I didn't understand that either. In the end i presumed that it was the line that would connect the two mirrors to form a right angled triangle...


On a separate note, could someone post a solution to 2010 Q.22??
Reply 383
anyone have solutions to the maths part of the 2011 paper?
Original post by Miles434
I didn't understand that either. In the end i presumed that it was the line that would connect the two mirrors to form a right angled triangle...


On a separate note, could someone post a solution to 2010 Q.22??


Thank you, Ive noticed a number of the questions are badly worded which can be confusing. I don't know how to write my solutions here, but I calculated the masses as;
green-24g and red-81g.
Reply 385
Has anyone got answers to 2011 24, or the long question about the archer? Cheersss
Reply 386
Original post by joemkcarr
Has anyone got answers to 2011 24, or the long question about the archer? Cheersss


24 I got:
alpha:beta:gamma
30:5:4

26 I got:
a)60ms^-1
b)50ms^-1
c)1s
d)5m above centre
e)5000N
f)0.2ms^-1
Reply 387
Original post by Miles434
I didn't understand that either. In the end i presumed that it was the line that would connect the two mirrors to form a right angled triangle...


On a separate note, could someone post a solution to 2010 Q.22??


These are my answers (by no means correct):
I'm leaving them as velocity squared so it looks less messy, but obviously for the answer you need to root them...

a) v^2=[k(x-l)^2]/m

b) v^=2[(x-l)(k(x-l)-20m)]/m

c) h=[(x-l)(k(x-l)-20m)]/20m
Original post by fayled
24 I got:
alpha:beta:gamma
30:5:4

26 I got:
a)60ms^-1
b)50ms^-1
c)1s
d)5m above centre
e)5000N
f)0.2ms^-1


How did you get 60m/s I got 85m/s by saying that 0.5mv^2=120*0.6, therefore to get v=root(72000)=60root(2)=85m/s
Reply 389
Original post by samkanwoods
How did you get 60m/s I got 85m/s by saying that 0.5mv^2=120*0.6, therefore to get v=root(72000)=60root(2)=85m/s


Its a bowstring so it stores elastic potential energy=0.5FL

It is non-calculator so getting root3600 which can be done mentally makes sense.

Getting 36J energy also makes sense for part 2 as 25/36x36=25.
(edited 11 years ago)
Original post by fayled
Its a bowstring so it stores elastic potential energy=0.5FL

It is non-calculator so getting root3600 which can be done mentally makes sense.


Oh **** I used worked done W=Fl, but I dont see why using W=KE wouldnt work either.
(edited 11 years ago)
Reply 391
Original post by samkanwoods
Oh **** I used worked done W=Fl, but I dont see why using W=KE wouldnt work either.


I originally thought to use Work done but it clearly doesn't work on the non calculator paper - if you get numbers you can't compute you're normally going wrong.

It is a bowstring so stores energy elastically hence you must use the EPE formula.
Original post by fayled
I originally thought to use Work done but it clearly doesn't work on the non calculator paper - if you get numbers you can't compute you're normally going wrong.

It is a bowstring so stores energy elastically hence you must use the EPE formula.


Makes sense I suppose. thanks
2011 question 24:

A radioactive source emits a parallel beam of alpha, beta and gamma radiation
and is placed 10 cm from a detector, which is sensitive to all forms of radiation
and receives 100 counts/sec.
When a sheet of aluminium of thickness 1 cm is placed in front of the detector,
the radiation level is seen to fall to 50 counts/sec.
When the source is taken away completely, the radiation levels are seen to
fall to 10 counts/sec.
When the source is placed 1 cm from the detector, the radiation levels are
seen to increase to 400 counts/sec.
In what proportion is the source emitting alpha:beta:gamma particles?


Have seen this type of questions in other past papers. Thought I could skip it every time but this time its a 4 mark question instead of one in the multiple choice part. Slightly worried now since the test is in a day's time.
Original post by fayled
Its a bowstring so it stores elastic potential energy=0.5FL

It is non-calculator so getting root3600 which can be done mentally makes sense.

Getting 36J energy also makes sense for part 2 as 25/36x36=25.


pulled back a distance of 0.6m doesn't necessarily mean the extension of the string = 0.6m does it?
The numbers shown by two dice are labelled d1 and d2; a score is constructed
from these by the expression: S = Ad1 + Bd2 + C, where A, B and C are
constants. Determine the values of A, B and C such that the range of possible
values for S covers all integers from 0 to 35, with an equal probability of each
score.

This one..I found C= -7 but I have no idea what I could do next
Reply 396
Original post by freakynerdlol
pulled back a distance of 0.6m doesn't necessarily mean the extension of the string = 0.6m does it?


yes...
Original post by fayled
yes...


does it?? :s
Reply 398
Original post by freakynerdlol
does it?? :s


If the string is pulled back a distance 0.6m then it must be extended by 0.6m. What else could it mean exactly?
Reply 399
Original post by fayled
These are my answers (by no means correct):
I'm leaving them as velocity squared so it looks less messy, but obviously for the answer you need to root them...

a) v^2=[k(x-l)^2]/m

b) v^=2[(x-l)(k(x-l)-20m)]/m

c) h=[(x-l)(k(x-l)-20m)]/20m


Wrong question.....

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