Physics .. Help please :)

[cHeStEr]

http://www.xtremepapers.me/CIE/Cambridg ... _qp_12.pdf

Q 1 11 15 17 22 23 24 26 35 and 40 please !
I know it's so much but .. Clearing doubts is must before exams

 

[Keeemoman]

Q1 you have to subtract 3-1.2=1.8
divide this 1.8 into 6 it then comes 0.3

Q11 you just need to subtract 15 from 16.4 and you ll get 1.4cm
Then try to find ot on the graph you will get it as 3.5N

Q15this is A as it didnt completely melt.

Q17this is A as the most energetic molecules escape because they have higher KE and the remainig average speed decreases because the more energetic
molecule with high speed leaves allowing the average to decrease.

Q22 is C since this is refraction(impossible to be diffraction) and they slow down as wavelength decreases and this wavelength is directly proportional to velocity.

Q23 is A since it is an echo which reflects so it moves the distance between the ship and the sea bed twice. therefore this 0.4 is divided into 2 allowing 0.2
to be multiplied into 1200.

Q24 frequency always remains the same but the pitch is same because both wave of p and q are formed in the same time. Here only the loudness increases
which is not asked.

Q26 is C because current remain same in series circuit.

Q35 It is A because AC current is needed and high voltage to prevent energy loss.

Q40 It is D because there was double the element before the half life and so therefore it will emit double the emissions before half life

Hope you understood it

 

[haochen]

answer 1
first we take the N of six disc by subtracting 3 and 1.2 to get 1.8
then we do cross mutiplication.
6 1.2
1 ?
so 1*1.2 = 1.2/6 = 0.3 N so the answer is "B"

answer 11
first we find the extension made by the object which is 16.4 -15 (original length)
=1.4 then go to the extension 1.4 and ull get 3.5 N (from the graph) which is "C"

answer 15
the answer is definitly "A" because the ice is still there so the graph is still in the melting process
and the temp stay at 0'C which is graph "A".

answer 17
the answer is "A" because the molecule must have more energy than the other so the answer is more energy
while if the high energy moleule go out to the environment so the speed of the molecule left in the water decrease.

answer 22
it definitly refracted and the speed of the wave can be told by the gaps between each wave ( line )
so the speed decrease and the answer is "C"

answer 23
use the formula of echo
speed=2d/t, u have speed and time, just replace them
d=(1200 * 0.4) / 2
the answer is "A" which is 240

answer 24
use the concept of frequency and pitch "if the frequency increase the pitch increase"
so in this case the frequency stay the same (same wavelength) so the pitch is the same
the answer is "D"

answer 26
the current in series circuit is the same so ammeter X and Y have the same value so both of them read it
which is "C"

answer 35
the answer is "A" because we need to use high voltage to transfer current because the higher the voltage the lower the heat loss
so one of the answer is high voltage. how do we produce a high voltage ???
by using a "step up" "tranformer". transformer only work with a.c. so the answer is a.c.
which is "A"

answer 40
the answer is "D" because the half life is at 70s and each second produces N (which is the half life)
so half life is by half ( /2 ) so u want it back so take the opposite which is ( *2 ) and they didnt tell u the emission
so its N and the answer is 2N

hope my explanation is clear
if u have doubt ill try my best to answer them

 

[Romani2011]

1 11 15 17 22 23 24 26 35 and 40
1- 3-1.2=1.8 then 1.8/6=0.3
11- The unloaded length is 15. and they told you when a weight is added the height becomes 16.4. 16.4-15=1.4 Then you go back to the graph and to the y-axis u go to 1.4 then see where it interacts with the line then see the x-axis which is 3.5
15- This ice is negative, so as u put it in room temperature its temperature increases, but as u know the melting point's temperature is always constant (same as boiling point). so the answer will be [A] . but in the case of D, boiling also occurs, but in this example there is no boiling, only melting so temperature stays constant.
17- Evaporation occurs when the energetic molecules on the surface break the bond and become more "energetic" and gain energy they leave the surface of the water. As these molecules that had high K.E. (speed) leave the surface, the molecules left will have less K.E. so the answer is [A]
22- It is obvious that it is refraction so we exclude diffraction. and there is rule for refracted waves : frequency of deep water = frequency of shallow water, and wavelength of deep is GREATER that wavelength of shallow, and SPEED OF DEEP WATER IS GREATER THAN SPEED OF SHALLOW WATER.
23- Speed=distance/time . in this case there is an error so it is DOUBLE the distance so it should be s=2d/t 1200=2d/0.4 therefore d=240.
24- Pitch is a quality of sound that depends on FREQUENCY of the sound of the wave. so frequency=pitch . and they both have the same frequency so it is [D].
26- Ammeters connected in series is the same where ever you put the ammeter.
35- As it is a LONG way from the village we must use HIGH voltage so to reduce loss of current. and u must know it works in a.c.
40- usually we divide but they said 70s EARLIER so we divide by 2
I hope this helps ardon:

 

[cHeStEr]

Thank you all ... The information which you gave was very helpful
Thank you all once again :Bravo: :friends:

 

[haochen]

ur welcm