IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: nid404 on April 15, 2010, 08:51:44 am
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This is crazy....I've tried everything to come to the answer!! >:( >:(
Please help
check the attachment for the diagram
At the moment of release, the shot is 2.3m above the ground. The shot has a mass of 7.3kg. Calculate the kinetic energy of the shot at the moment of release....
How on earth is the ans 1713J am I using the wrong velocity...we're supposed to use the resultant right? in the direction of 12m/s ???
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Help? ::) Pleeaasseeeee :-*
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http://books.google.co.in/books?id=4GUxeWap9qcC&pg=PA110&lpg=PA110&dq=At+the+moment+of+release,+the+shot+is+2.3m+above+the+ground.+The+shot+has+a+mass+of+7.3kg.+Calculate+the+kinetic+energy+of+the+shot+at+the+moment+of+release&source=bl&ots=BiPH-ngkim&sig=4FJ2IoVev9CwHiz_DWyXtG_f6WQ&hl=en&ei=9crGS7qlIpK4rAevs53zCQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAYQ6AEwAA#v=onepage&q=At%20the%20moment%20of%20release%2C%20the%20shot%20is%202.3m%20above%20the%20ground.%20The%20shot%20has%20a%20mass%20of%207.3kg.%20Calculate%20the%20kinetic%20energy%20of%20the%20shot%20at%20the%20moment%20of%20release&f=false (http://books.google.co.in/books?id=4GUxeWap9qcC&pg=PA110&lpg=PA110&dq=At+the+moment+of+release,+the+shot+is+2.3m+above+the+ground.+The+shot+has+a+mass+of+7.3kg.+Calculate+the+kinetic+energy+of+the+shot+at+the+moment+of+release&source=bl&ots=BiPH-ngkim&sig=4FJ2IoVev9CwHiz_DWyXtG_f6WQ&hl=en&ei=9crGS7qlIpK4rAevs53zCQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAYQ6AEwAA#v=onepage&q=At%20the%20moment%20of%20release%2C%20the%20shot%20is%202.3m%20above%20the%20ground.%20The%20shot%20has%20a%20mass%20of%207.3kg.%20Calculate%20the%20kinetic%20energy%20of%20the%20shot%20at%20the%20moment%20of%20release&f=false)
here's the complete question
q 52
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This is crazy....I've tried everything to come to the answer!! >:( >:(
Please help
check the attachment for the diagram
At the moment of release, the shot is 2.3m above the ground. The shot has a mass of 7.3kg. Calculate the kinetic energy of the shot at the moment of release....
How on earth is the ans 1713J am I using the wrong velocity...we're supposed to use the resultant right? in the direction of 12m/s ???
the right answer is 713J not 1713J
because K.E=0.5(7.3)(13.97....)^2
K.E=712.919....... J
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I got the same answer....
But the back of the book says 1713 :(
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I got the same answer....
But the back of the book says 1713 :(
it might be a printing error
add the 1 to 713 by mistake
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Let's hope so...
Makes me feel good ;D :P
Thanks tho
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How did you get 13.97 anyway?
12+3cos54=13.76..
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How did you get 13.97 anyway?
12+3cos54=13.76..
the resultant velocity
v=(12cos54+3)^2 + (12sin54)^2
then take the sqr root of the ans
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dont worry nid..it's 713 definitely..
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Oh.. i see.
But if we resolve 3 in the direction of 12 (12+3cos54).. is that a slight variation of answer or a wrong way?
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a wrong way.. 3 is already in a horizontal direction..dont confuse your self
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Oh.. i see.
But if we resolve 3 in the direction of 12 (12+3cos54).. is that a slight variation of answer or a wrong way?
u cant resolve 3 , because 3 is in the horizontal direction
but the 12 , can be resolved in the vertical and horizontal directions
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If I take the direction of 12 as y-axis?
And add the component of 3 in that direction?
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If I take the direction of 12 as y-axis?
And add the component of 3 in that direction?
u cant , the direction of the y-axis is vertical
12 is not vertical
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ok....june 03 paper 1 q20
I thought it should be B, but ans turns out to be A....can some1 explain plz
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which board ??
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which board ??
CIE
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2 mins
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2 mins
sure thanks
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ok....june 03 paper 1 q20
I thought it should be B, but ans turns out to be A....can some1 explain plz
Now we both know the answer is either A or B..
Well its kind of impossible to choose B! You can not have a 9 metres straw! lol
thats the main point actually..
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Now we both know the answer is either A or B..
Well its kind of impossible to choose B! You can not have a 9 metres straw! lol
thats the main point actually..
but reason....
when pressure is reduced by 10%...pressure would be 90% right....
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alright..her's ur reason..in order for straw to go up..there must be change of pressure..
here..change of pressure= p-p/9=p/10
got it?
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The pressure downwards would be 90%, and the pressure "upwards" 10%.
And this upward pressure is the one that's going to push the liquid along the straw.
I dont fully understand this question too, but that's what i could guess.
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alright..her's ur reason..in order for straw to go up..there must be change of pressure..
here..change of pressure= p-p/9=p/10
got it?
so pressure on the top is 9/10....pressure on the liquid is atmospheric pressure...difference is 1/10= hdg
so u equate the difference in pressure? If so, then i got it
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hey nid :D
is this bk gd?
say if u study for the exam from it, is it enough????
thx ;)
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Well I find good....yup i guess should be enough..
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CIE
M/J 04 Q13)
I don't like it when they don't keep the pivot at the centre :P
Please explain how the weight is distributed....i s at physics...like totally...
Thank you
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When I get home
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When I get home
ok,....also of the same paper....q25 n 26
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Sir can u do a video on wave formation please....like for the 25th question... :-\
thank you
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5 minutes nid..
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5 minutes nid..
yaa sure...U knw i don't favour physics ::)
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scanning q. 13 lol
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scanning q. 13 lol
take ur time
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now for question 25...
we both know that P is moving downwards..so the only possible answer is A..
If u cudnt imagine it, get a rope, and start making waves..u will find that point p is moving downwards..
check out this site:
http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html
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now for question 25...
we both know that P is moving downwards..so the only possible answer is A..
If u cudnt imagine it, get a rope, and start making waves..u will find that point p is moving downwards..
check out this site:
http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html
hmm....when they say the wave is travelling from the left to the right....it means it's going from Q to P right ???
mahn i jst can't figure physics...
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question 26:
we know that E is proportional to A^2..or energy is proportional to the sqaure of amplitude, and Enegy is proprtional to surface area..
therefore, when the amplitude is doubled, energy is quadripled, so it is now 4E..
and when Sis halfed, E is halfed, and so the answer is 2E..
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hmm....when they say the wave is travelling from the left to the right....it means it's going from Q to P right ???
mahn i jst can't figure physics...
lol its alright..but these r waves nid! not just ordinary people walking! lol.
so its not possible to go from P to Q...things must be going up and down.
um sorry i cannt explain more than that..did u check the site i wrote down? :'(
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lol its alright..but these r waves nid! not just ordinary people walking! lol.
so its not possible to go from P to Q...things must be going up and down.
um sorry i cannt explain more than that..did u check the site i wrote down? :'(
I checked...but i don't figure waves....no problem...i knw what ur trying to say....but the thing is i don't understand the motion....
Thanks for trying tho...:)
I'll wait for astar to get me something on waves..
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Question 13:
I hate my scanner! >:( >:(
lol..anyways..u must draw the whole system first..
Just after 0.5 metres from the pivot, put the 50 N force..Sine the rod is uniform, u must place its weight at the middle..which is 1.5 metres from either sides..
Then, u take moments about the pivot:
Wx1 = 50x 0.5
therefore, W=25 N..
got that?
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Question 13:
I hate my scanner! >:( >:(
lol..anyways..u must draw the whole system first..
Just after 0.5 metres from the pivot, put the 50 N force..Sine the rod is uniform, u must place its weight at the middle..which is 1.5 metres from either sides..
Then, u take moments about the pivot:
Wx1 = 50x 0.5
therefore, W=25 N..
got that?
Yup totally....stupid me ::)
thanks
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Yup totally....stupid me ::)
thanks
lol anytime..
wut about q. 26? u got it?
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Im getting 4E as the answer...but it's 2E :-\ :-\
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question 26:
we know that E is proportional to A^2..or energy is proportional to the sqaure of amplitude, and Enegy is proprtional to surface area..
therefore, when the amplitude is doubled, energy is quadripled, so it is now 4E..
and when Sis halfed, E is halfed, and so the answer is 2E..
still...?
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still...?
oops i didn't see that
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thank you
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thank you
lol no prblm :D
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for june 04 q13
the weight of 50N acts at center of pivot so at 1.5 m
so there's a difference of 0.5 m at the pivot as 1.5-1=0.5 m
always we take moments from pivot
so 0.5*50=25N
since F1D1=F2D2
so 50*0.5=X*1
X=25N
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for june 04 q13
the weight of 50N acts at center of pivot so at 1.5 m
so there's a difference of 0.5 m at the pivot as 1.5-1=0.5 m
always we take moments from pivot
so 0.5*50=25N
since F1D1=F2D2
so 50*0.5=X*1
X=25N
yup i got it thanks :)
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~ A.F ~
for question 25 i don't get when they say in the examiner's report "If only candidates had used their
pencils to draw in, on the paper itself, the new wave a little bit later in time they would have seen clearly that
P must go down and that Q barely moves - if they tried Q down as well they would not have been able to
give that as an answer because it is not there"
do u have any idea what they mean? ???
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No prob :D
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Q13 1*W=0.5*50 so W=25
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The wave is moving from left to right so try drawing the wave in again but a little to the right
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The wave is moving from left to right so try drawing the wave in again but a little to the right
I'm really bad at waves :'(
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I'm really bad at waves :'(
awwwwww...rofl..JK
what about ur tutour? cudnt he explain it to you? :-\
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for determining the wavelength by using a laser beam and young slits experiment what does this passage mean ?
:
the slits are a fraction of a millimetre in width. since the wavelength of light is less than a micrometer, this gives a small
amount of diffraction in the space beyond, if the slits were narrower , the intensity of the light would be too low
for visible fringes to be achieved
could someone plzzzz explain it !!!!!! thx
waves are so hard :S
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awwwwww...rofl..JK
what about ur tutour? cudnt he explain it to you? :-\
my tutor s*cks....like srsly.
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for determining the wavelength by using a laser beam and young slits experiment what does this passage mean ?
:
the slits are a fraction of a millimetre in width. since the wavelength of light is less than a micrometer, this gives a small
amount of diffraction in the space beyond, if the slits were narrower , the intensity of the light would be too low
for visible fringes to be achieved
could someone plzzzz explain it !!!!!! thx
waves are so hard :S
the amount of diffraction depends on the wavelength of the wave relative to the gap width..if the gap is smaller, then greater diffraction..thats basically it! lol
like since the gap is much wider than wavelength, diffraction would be small..
got that?
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the amount of diffraction depends on the wavelength of the wave relative to the gap width..if the gap is smaller, then greater diffraction..thats basically it! lol
like since the gap is much wider than wavelength, diffraction would be small..
got that?
so diffraction would be best...if the wavelength is almost the same as the gap?
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my tutor s*cks....like srsly.
As in your teacher or hired tutor ?
Tutors suck up your money and may/may not what they are trying to teach you. I dont trust them.
Teachers have a lackadaisical attitude and conveniently forget vital points. I dont trust them either.
Who do trust ?? THE DISCOVERY CHANNEL !!! QUESTION EVERYTHING !!!
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Exactly
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Exactly
rofl
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AS CIE PHYSICS
paper 2 november 2004
Q 1 bii
Q 3d
Q7b
PLEASE RILI URGENT
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AS CIE PHYSICS
paper 2 november 2004
Q 1 bii
Q 3d
Q7b
PLEASE RILI URGENT
5 minutes
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AS CIE PHYSICS
paper 2 november 2004
Q 1 bii
Q 3d
Q7b
PLEASE RILI URGENT
Q1 bii:
Area= o.25xpiexsqaure of diameter
therefore the percentage uncertainty of area=persentage uncertainty of diameterx2
Q7b:
will be less deviated..will cross the first path, and bend beyond it with a smaller angle..
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As in your teacher or hired tutor ?
Tutors suck up your money and may/may not what they are trying to teach you. I dont trust them.
Teachers have a lackadaisical attitude and conveniently forget vital points. I dont trust them either.
Who do trust ?? THE DISCOVERY CHANNEL !!! QUESTION EVERYTHING !!!
I meant the one in school....i don't have a private tutor :-\
I guess i'll have to get one now... :'( :'(
I was so happy abt chem n bio...i forgot abt phy :-[
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I meant the one in school....i don't have a private tutor :-\
I guess i'll have to get one now... :'( :'(
I was so happy abt chem n bio...i forgot abt phy :-[
lol its alright..Astar is here for you..
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.......and me ;D
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oh yes thank you. :)
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oh yes thank you. :)
And I can offer some up lifting quotes from sgvaibhav. An acclaimed author on ''The Momentary Dynamics of Curves''
LOL Just kidding man... thats the last time Im gonna ssay that. YOu got agree that was funny !!!
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Q1 bii:
Area= o.25xpiexsqaure of diameter
therefore the percentage uncertainty of area=persentage uncertainty of diameterx2
Q7b:
will be less deviated..will cross the first path, and bend beyond it with a smaller angle..
is this some kind of rule to find such uncertainities? and what is the main formula we have to use here? and could u do question 3.
thx :o ;D ;D ;D ;D
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is this some kind of rule to find such uncertainities? and what is the main formula we have to use here? and could u do question 3.
thx :o ;D ;D ;D ;D
lol no prblm.. and YES its a rule..for example if a radius of a sphere has uncertainty of 2%, and volume =4/3 x pie x r^3, then uncertainty of volume= 2x 3= 6%..and um out now..when i go home i'll do Q.3..sorry
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hey guys!!
can u help me out in question 6 of june 2008 p1 CIE physics i can't really figure out the answer :-\
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hey guys!!
can u help me out in question 6 of june 2008 p1 CIE physics i can't really figure out the answer :-\
2 minutes
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The answer is C..This is actually an A2 question..Its like in circular movement, acceleration towards the centre, and direction of movement tangenital to path, i.e perpendicular..From your O-level you can remember that velocity in this case changes in direction only, not MAgnitude..
thats why speed is constant, direction changes
got that?
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Thanks loadz ;D
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Thanks loadz ;D
anytime ;)