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

[wooowooowoo]

it was stable because there was no weight and the centre of mass was at M.
but when there they hang the weight at the tail, the centre of mass is at the pivot.

Ok I guess I did a different paper, lol.

 

[Dandelion]

what toy and bird. the toy is the bird.

lol sorry i mean the counter weight is lighter than the bird. heheheh

 

[omglaigcse]

lol sorry i mean the counter weight is lighter than the bird. heheheh

who said? the counter weight is heavier than the bird

 

[Dandelion]

who said? the counter weight is heavier than the bird

isnt the answer of finding the counter weight in no.1 was 0.5 or 0.6 ? i cant recall. and the bird is like 1 kg or some shit ? i can hardly remember but yeah

 

[wooowooowoo]

isnt the answer of finding the counter weight in no.1 was 0.5 or 0.6 ? i cant recall. and the bird is like 1 kg or some shit ? i can hardly remember but yeah

1.5 and 0.6

 

[omglaigcse]

1.5 and 0.6

oh really. crap i dont know. but even so, it will still move clockwise cause there's no anticlockwise moment.

 

[Moi]

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

but you have to subtract 14 from 52, because the graph doesn't go all the way down... to the very bottom

 

[Moi]

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.

That's what i did and that's what i got..... 1.6 days

 

[Moi]

If you have to add the background radiation again (at the end) so there is no need of reducing it in the starting, right ?

you'll subtract the background radiation so you'll know the REAL count for the REAL Radition...without background, so it's 19. But when you draw, since you have background radiation, you'll have to add it so the graph will be corret!

 

[kareem]

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.

oh well i hope i got 2 marks for that one if your right , i think i lost all the magnetism marks (or most of them) and possible some on the electric charge and like 2 on the energy one so ye i hope its an A if boundaries are low , or B if somehow theyre high

 

[Daxter]

How many marks was the bulb question..cause I got the final answer wrong but the working is all there...I left the last question cause I don't have time..everything else seems to be copacetic so I guess 3 + what ever the marks for the bulb question is what I believe I lost

 

[Chucky]

How many marks was the bulb question..cause I got the final answer wrong but the working is all there...I left the last question cause I don't have time..everything else seems to be copacetic so I guess 3 + what ever the marks for the bulb question is what I believe I lost

if all working which leads to 8 or 9 bulbs as an answer , then you get 3
if half the work is done then 2
just for writing the equation 1.

oh well i hope i got 2 marks for that one if your right , i think i lost all the magnetism marks (or most of them) and possible some on the electric charge and like 2 on the energy one so ye i hope its an A if boundaries are low , or B if somehow theyre high

A boundary will be VERY low, so don't worry.

That's what i did and that's what i got..... 1.6 days

I'm so stupid! I forgot to add it back.

 

[Chucky]

it's tilting to the right. the right is the lower side, the tail with the weight hanging on it. it's tilting to that side, and there's something heavy on it. surely it will move that way

its tilted! the additional moment is no longer applied.

think of it as a see saw with two kids on each side
the kid on the right goes down causing the one on the left to go up

now the kid on the right LEAVES, will the see saw still be in the same clockwise position? no! it will fall back anti clockwise.


that was a VERY bad example but it should get the message accross.

 

[omglaigcse]

its tilted! the additional moment is no longer applied.

think of it as a see saw with two kids on each side
the kid on the right goes down causing the one on the left to go up

now the kid on the right LEAVES, will the see saw still be in the same clockwise position? no! it will fall back anti clockwise.


that was a VERY bad example but it should get the message accross.

the kid on the right did not leave. it is still hanging alright. the weight is there
AND THERE IS NO KID ON THE LEFT. the kid on the left is at the pivot cause the centre of mass is at the pivot.
and you cant use a see saw.
SEE SAW HAS A GROUND. this doesnt. -_-

 

[JOEJOE]

The correct refractive index is 1.56 if u didnt get that ur gonna loose lotta marks

and efficiency is 33.6% maybe
also, total force (bird quesition) = 21N
the answer about explain the radio activity was becoz its random and slow process bla bla right?
for the dot and the charge u should draw like 5 arrows inwards right?
Plus... what was the answer for the last question about radioactivity ( why its not enuff precautions etc..)

 

[Stormcry72]

how do you know that the background radiation is exactly is 14 ?? it varies.. so i dont think making any calculation with the background radiation is valid. all i did was just read from the graph and i got 2.6 days. in any textbook, when they show how to find the half life time, they just read from the graph tho. well i dont know, this is my point of view

yeah 14 is the background radiation because the graph levels off in the end at 14, showing that all activity from the radioactive substance is over, what remains is background radiation

and another reason why 2.6 isn't correct is because if u double it, i.e after 5.2 days, the counts per minute should be exactly half of that on 2.6 days, and it was not

 

[JOEJOE]

Did it say 14 background radiation in the question??

 

[Stormcry72]

Did it say 14 background radiation in the question??

no but you have to make it out from the graph,
read my reply above

 

[kareem]

The correct refractive index is 1.56 if u didnt get that ur gonna loose lotta marks

and efficiency is 33.6% maybe
also, total force (bird quesition) = 21N
the answer about explain the radio activity was becoz its random and slow process bla bla right?
for the dot and the charge u should draw like 5 arrows inwards right?
Plus... what was the answer for the last question about radioactivity ( why its not enuff precautions etc..)

no .. refractive index was much lower and the efficiency is right i got a similar answer

 

[omglaigcse]

no .. refractive index was much lower and the efficiency is right i got a similar answer

nope. the refractive index is correct. 1.56.