Physics Pp:3-Variant 2- Discussing Answers!!

[Stormcry72]

it's way more. you have to deduct background radiation which was around 14 counts per minute.
you find that from the graph (it is the point after which the counts do not decrease anymore)
52-14= 38
38/2= 19 counts per minute
find out how long it took to come to 19 counts per minute.
should be more than 3 days.

but after you get 19 counts per minute you have to add the background radiation again because remember, the graph shows counts/minute INCLUDING background radiation

so you add 14 to 19 and you get 33
number of days to reach 33 is 1.6 days

and the bulb question, i got the answer as 8 or 9 but unfortunate for me, i solved it after the paper was taken......... no time for writing it down
i could only deduce the total resistance of the circuit if the current was 0.9A, which is 266.67 ohms, after that the teacher snatched my paper
(p.s. i left this question for the last, everything else i finished)

 

[yuyu_373]

rotates back

yaa i wrote it like ths bt my friends told me its wrong!!

 

[igcsedude_Jor]

i rmmber there was a question where we had 2 find out the percentage efficiency (the tidal question, which was the sec question i guess..) wat was the answer?
was the answer 0.6 kg for the weight of that thingi in the equilibrium question?? 21N for the upward force *exerted by the pivot*?? was the following answer anti or clockwise?? were we supposed 2 write: cz radioactivity is random and unpredictable, for the first question in radioactivity??in the magnetisim question, wat were we supposed 2 draw around that dot??? wat was answer for the second part of the waves question?? was the gravitational potential energy lost by water 33900??
wat were the current and resistance of each bulb? wat was the answer for the last question in radioactivityy (long forcepts thingi)
sryy 4 the too many questionss and thankss

 

[Abdullah Ali]

For the bulbs and fuse question... was it specified that the circuit is connected in series or parallel????

 

[ahmed99]

For the bulbs and fuse question... was it specified that the circuit is connected in series or parallel????

It was series

 

[Aay-Jay Bird <3]

i feel like everything i studied for hard, like CRO and the peek to peek distance (that i still don't get it) and the Specific heat capacity , pressure, density ... all didn't come, like i studied them for nothing!! they're the easy ones and didn't come..so frustrating!!

What's peek to peek distance?

 

[kareem]

24 hours have passed so... lets start discussing!
1) Please someone tell me what did you get for the Bulb question?? I didn't have time to solve the Qs so i just wrote the first number that came to my mind..4
2) When the magnet enters the coil, the force induced is upward or downward ? I didn't know it so i guessed it and wrote downward!
3)What did you get for the radioactivity life?? I got 1.6 days
4)The question about the tidal thingy, the water goes left or right ?? (i didn't even know what the question was about)
5) When drawing the red ray (reflection and Refraction) how do you do it ? I traced the reflection part over the blue one, but didn't do the refraction part
6) The gate where NOR, & the two ones are Not and OR Right ?? The Y had 0 (Low) and Z had 1 (High)

That's all i have to ask for now.. Note that i left some questions un answered due to time limit !!

for 3 i got 2.6 days , you had to use the graph i think

 

[omglaigcse]

this is for the light bulb.
i really think the answer is 6, but i can only get 7 with my working.
so the voltage is 240V.
the maximum current would be 0.9A.
so here, we can calculate the total amount of resistance that you can have for 0.9A.
so that would be 240=0.9R
R=266 2/3, so around 267 ohms.

267 ohms is for x number of lamps.
and you know the resistance of one lamp is 5% more, which is 8 x 105/100 = 8.4 ohms.
so 267/x = 8.4
x = 32. you have to round it up because the more lamps you have, the more resistance you have and a lower current.
but you have to understand that 8 broken lamps would cause the fuse to blow, so it has to be less than 8, which is 7.

YOU CAN TEST THE ANSWER.
if 7 lamps blow, there would be 33 lamps.
33 x 8 = 264ohms . this is the total resistance.

try it in the equation.
240 = 264I
I = around 0.91, around there.

if you have 8 lamps that blow, there would be 32 lamps.
32 x 8 = 256I
I = 0.94A SO DEFINITELY THE FUSE WOULD BLOW.
any answer 8 or more is WRONG!!!

i really think it's 6 cause it's less than 0.9A, but i got 7 so...

 

[omglaigcse]

and for the bird one, it rotates clockwise.
this is because the centre of mass is at the pivot, there is no distance. so there is no moment at all for anticlockwise.
and there is clockwise moment, therefore it moves clockwise
i got it wrong, but clockwise should be right

 

[Moi]

guys, do you know the answer for the stupid bird ? does it stay stationary when rotated or it rotates back anticlockwise ? explain too please

i wrote it will rotate anticlockwise in order to gain qulibrium back, beacuse the force from our finger caused it to move clockwise, so, when we remove our finger, it will go back to how it was.. not sure, but this is what i wrote!!

 

[Moi]

but after you get 19 counts per minute you have to add the background radiation again because remember, the graph shows counts/minute INCLUDING background radiation

so you add 14 to 19 and you get 33
number of days to reach 33 is 1.6 days

and the bulb question, i got the answer as 8 or 9 but unfortunate for me, i solved it after the paper was taken......... no time for writing it down
i could only deduce the total resistance of the circuit if the current was 0.9A, which is 266.67 ohms, after that the teacher snatched my paper
(p.s. i left this question for the last, everything else i finished)

so 1.6 days is correct ??? That's what i got !!

 

[Moi]

i rmmber there was a question where we had 2 find out the percentage efficiency (the tidal question, which was the sec question i guess..) wat was the answer?
was the answer 0.6 kg for the weight of that thingi in the equilibrium question?? 21N for the upward force *exerted by the pivot*?? was the following answer anti or clockwise?? were we supposed 2 write: cz radioactivity is random and unpredictable, for the first question in radioactivity??in the magnetisim question, wat were we supposed 2 draw around that dot??? wat was answer for the second part of the waves question?? was the gravitational potential energy lost by water 33900??
wat were the current and resistance of each bulb? wat was the answer for the last question in radioactivityy (long forcepts thingi)
sryy 4 the too many questionss and thankss

I never got the time to answer the efficieny, just wrote the equation. Yes the mass is 0.6 and the force is 21 N
I'm not sure which, but i wrote anticlockwise.
You were supposed to draw lines with arrows going to the dot (not out)
I think i also got 33900, so i think it's right!
The last question, i didn't get the chance to read the question since they said pens down, so i just read a couple of words and wrote that radiation is damgerous for us !!
The rest, i don't remember !

 

[Moi]

for 3 i got 2.6 days , you had to use the graph i think

i did use the graph, and got 1.6 .. i think it's the correct answer !

 

[Dandelion]

the

and for the bird one, it rotates clockwise.
this is because the centre of mass is at the pivot, there is no distance. so there is no moment at all for anticlockwise.
and there is clockwise moment, therefore it moves clockwise
i got it wrong, but clockwise should be right

the centre of mass is not at the pivot.. its to the left of the pivot. isnt it shown in the diagram itself ?

 

[Dandelion]

ughh the number of bulbs. its too confusing. as long as there is 8.4 ohms and 8.4 x 0.9 and 240/(8.4x0.9), i should be getting a few marks.
better than zero.

 

[kareem]

i did use the graph, and got 1.6 .. i think it's the correct answer !

it goes from 51 and halves to become 26 and if u look at graph it goes 2.6 i double checked , and for the bird thing i got anticlockwise

 

[Chucky]

but after you get 19 counts per minute you have to add the background radiation again because remember, the graph shows counts/minute INCLUDING background radiation

so you add 14 to 19 and you get 33
number of days to reach 33 is 1.6 days

and the bulb question, i got the answer as 8 or 9 but unfortunate for me, i solved it after the paper was taken......... no time for writing it down
i could only deduce the total resistance of the circuit if the current was 0.9A, which is 266.67 ohms, after that the teacher snatched my paper
(p.s. i left this question for the last, everything else i finished)

Yeah I knew 4 days was too long, thanks.
but I should get 3 out of 4 for understanding that we deduct and the math.

dont mind losing 1 mark, overall I guess I lost only 8-9 marks. WOW!

 

[Chucky]

rotates back

must mention the type clockwise or anti clockwise.

it is anti clockwise by the way.
when we were all young we played with toys like these, funny we should sit for an exam with a question regarding one too.

 

[omglaigcse]

the

the centre of mass is not at the pivot.. its to the left of the pivot. isnt it shown in the diagram itself ?

no did you read part 2 of question (a)?
when there is the weight thingy at the tail, the centre of mass is at the pivot.

 

[Chucky]

it goes from 51 and halves to become 26 and if u look at graph it goes 2.6 i double checked

but you have to deduct background radiation which was 14
making your inital count 52-14= 38

divide that by 2 = 19
add background radiation again 19+14= 33
now find how long it took to reduce to 33 counts
should be 1.6 I guess

but I wouldnt know, i forgot to add back the background radiation. but it will not exceed 2.5 days I guess, there's always a range.