AS Physics (9702) Paper 22 Answers and Discussion

[Your-Blood]

probably 28-33
i think so , since majority had that graph wrong ..and wave

28-33 NOWAY.

It must be around 44,45.I believe that most of the candidates found the graphs and stationary wave difficult but almost every average student aced the other straight forward questions.

Any tips on solving paper 1 questions? That thing really screws me up :/

Practice as much past papers as you can. Read examiner reports ,take help from friends.Identify your weak areas and concepts, revise your weak chapters.

 

[mohsinSK]

Please help. ECF Problem :/

Guys I have almost everything correct but I want to know, I think I messed something up in calculating the current in Question 6. I DID write P=V2/R and P=VI. The power I calculated was correct. I think I messed something up in the calculator and got a completely different value of current. Using that I calculated the charge in 2.60Ms and for the last part I divided the current by elementary charge to get the no. of electrons per second. I wanna know if I can get ecf on the rest of my answers after I calculated the current incorrectly? How many marks will I lose?

 

[Your-Blood]

Please help. ECF Problem :/

Guys I have almost everything correct but I want to know, I think I messed something up in calculating the current in Question 6. I DID write P=V2/R and P=VI. The power I calculated was correct. I think I messed something up in the calculator and got a completely different value of current. Using that I calculated the charge in 2.60Ms and for the last part I divided the current by elementary charge to get the no. of electrons per second. I wanna know if I can get ecf on the rest of my answers after I calculated the current incorrectly? How many marks will I lose?

You would get marks for just calculating power and charge.

For the last part you have to divide charge by elementary charge not current.

 

[Your-Blood]

Physics gt is near about 30-36
it can never go to 40 and it wont , if u / or candidates of ur centre did it , that doesnot mean , others also did it
if u deduct that 12 mark...and generally people felt time shortage ...at my centre

Sorry I was suppose to write 35,36.

 

[misof'tegame]

This thread is only for those who wish to check answers, and I may not have all the answers correct, but I'll try and edit this post and make sure all the correct answers have been uploaded for you all to check!


Question 1: Power base units : kgm^2 s^-3
C has no unit (easy to prove)
speed of wind: 9.44 m/s

Question 2: Accel-time graph
a= 3.5
so the graph is a flat line at a=3.5 upto t=2 seconds. then it becomes zero after 2s

Momentum time graph:
momentum is 16.4 Ns at t=2s
line has a constant gradient upto t=2s and then becomes flat.

Question 3: Moments
Tsin50= 22.8 N
Weight of O is approx 19N
Mass is 19/9.81
A force has to be exerted by A to ensure there is no net force of the rod

Question 4: Brownian Motion
Apparatus: Light source, closed GLASS box with smoke particles in side and a microscope to view the particles from top
What we notice: Smoke particles moving in random zig-zag manner.
Properties of gas we can conclude: Have high energy in the particles and move in a random manner OR gasses fill up the volume of the container.

Question 5: Stationary Waves
Wavelength= 0.8m
How stationary waves are formed:
Progressive waves generated travel to the other end and REFLECT back. The reflected waves then SUPERIMPOSE with the original progressive waves and create regions of max disp (anti-nodes) and min disp (nodes).
Nodes correctly labelled.
length of PQ is 1.2m
Stationary wave at t+5ms is a straight line drawn from P to Q

use frequency to find the time period T of the wave which is 0.02s
t+5ms= 0.025s which is 1/4 of the wave period.
therefore the wave is a flat line.

Question 6: Electricity
Power= 3200W
Current = 13.3 A
Charge= Current X Time
Electrons flowing per second: 8.34 X 10^19

Question 7: Radioactivity
Alpha particle is a helium nuclei so the WXYZ part was easy
Mass doesn't seem to be conserved because MASS ENERGY is conserved. The change in mass is converted to other forms of energy such as K.E in the particles or photons OR gamma radiation.
Radioactivity is spontaneous meaning it is not affected by external factors such as pressure.

That's about it. If you have confusions DO NOT PM me. Ask here and others MAY help you out.

the line goes flat for the resultant displacement of the two waves...but there they dint ask us to draw the resultant displacement..they asked us to draw the position of the wave after 0.5t...so wouldnt it be just opposite to the wave already given by them?

 

[drewrock]

wht do u thnk abt the grade trashold of this paper..?

 

[FRENZYAMU]

Did we have to label a node at point P?
Also, in the moment's question, they gave us T which was 30 N.
30sin50 = 22.98 N
round it off to 2 sf and we get 23 N.

ws there a question about labelling a node ?????,.......crap !

 

[Beaconite007]

ws there a question about labelling a node ?????,.......crap !

Nodes and antinodes both, if I recall correctly.

 

[HorsePower]

ws there a question about labelling a node ?????,.......crap !

yeah, even i didnt look at it at first.... it was mentioned beneath the wave

 

[pakiboy]

are

This thread is only for those who wish to check answers, and I may not have all the answers correct, but I'll try and edit this post and make sure all the correct answers have been uploaded for you all to check!


Question 1: Power base units : kgm^2 s^-3
C has no unit (easy to prove)
speed of wind: 9.44 m/s

Question 2: Accel-time graph
a= 3.5
so the graph is a flat line at a=3.5 upto t=2 seconds. then it becomes zero after 2s

Momentum time graph:
momentum is 16.4 Ns at t=2s
line has a constant gradient upto t=2s and then becomes flat.

Question 3: Moments
Tsin50= 22.8 N
Weight of O is approx 19N
Mass is 19/9.81
A force has to be exerted by A to ensure there is no net force of the rod

Question 4: Brownian Motion
Apparatus: Light source, closed GLASS box with smoke particles in side and a microscope to view the particles from top
What we notice: Smoke particles moving in random zig-zag manner.
Properties of gas we can conclude: Have high energy in the particles and move in a random manner OR gasses fill up the volume of the container.

Question 5: Stationary Waves
Wavelength= 0.8m
How stationary waves are formed:
Progressive waves generated travel to the other end and REFLECT back. The reflected waves then SUPERIMPOSE with the original progressive waves and create regions of max disp (anti-nodes) and min disp (nodes).
Nodes correctly labelled.
length of PQ is 1.2m
Stationary wave at t+5ms is a straight line drawn from P to Q

use frequency to find the time period T of the wave which is 0.02s
t+5ms= 0.025s which is 1/4 of the wave period.
therefore the wave is a flat line.

Question 6: Electricity
Power= 3200W
Current = 13.3 A
Charge= Current X Time
Electrons flowing per second: 8.34 X 10^19

Question 7: Radioactivity
Alpha particle is a helium nuclei so the WXYZ part was easy
Mass doesn't seem to be conserved because MASS ENERGY is conserved. The change in mass is converted to other forms of energy such as K.E in the particles or photons OR gamma radiation.
Radioactivity is spontaneous meaning it is not affected by external factors such as pressure.

That's about it. If you have confusions DO NOT PM me. Ask here and others MAY help you out.

are these all correct?

 

[pakiboy]

i'm still confused for how to draw the momentum graph
first it was a straight line showing constant gradient and then the momentum becomes constant and there is a straight horizontal line for 2 seconds right?

 

[mohsinSK]

You would get marks for just calculating power and charge.

For the last part you have to divide charge by elementary charge not current.

excuse me? it was number of electrons PER SECOND. you were not supposed to divide the charge calculated in the previous part. Q=It. t = 1 for 1 second. Hence Q=I. So that is how you divide the value of the charge which is equal to the current calculated by the elementary charge!

 

[Beaconite007]

excuse me? it was number of electrons PER SECOND. you were not supposed to divide the charge calculated in the previous part. Q=It. t = 1 for 1 second. Hence Q=I. So that is how you divide the value of the charge which is equal to the current calculated by the elementary charge!

The charge you calculated in the previous part was the total charge in the given amount of time (Something in Megaseconds)
The next question asked you to calculate the number of electrons per second, so you had to divide the charge obtained in the previous part by the elementary charge of an electron (1.6*10^-19 C)
After that you were supposed to divide the calculated value by the time.

 

[Your-Blood]

excuse me? it was number of electrons PER SECOND. you were not supposed to divide the charge calculated in the previous part. Q=It. t = 1 for 1 second. Hence Q=I. So that is how you divide the value of the charge which is equal to the current calculated by the elementary charge!

http://www.qfak.com/education_reference/science_mathematics/?id=b649471#.UY60uCODrrc

 

[Beaconite007]

http://www.qfak.com/education_reference/science_mathematics/?id=b649471#.UY60uCODrrc

Goddamit man, you scared me for a second D:
I thought my method was wrong.
I could've saved valuable space if I had just divided the current by the elementary charge instead of multiplying it with the time which I was going to divide later on anyway >.<

 

[FRENZYAMU]

yeah, even i didnt look at it at first.... it was mentioned beneath the wave

shoooot,,,,,how much marks was it worth ????

 

[rose1700]

shoooot,,,,,how much marks was it worth ????

3

 

[FRENZYAMU]

3

ahhhh crrrap ! ws it an completely diff part or part of drawing the wave ???

 

[Umar Zain]

For question 1 :
last part : we were suppose to write speed 9.44 or 9.4
I think I wrote 9.4 :/

For question 3:
For mass I did 19/9.81
But wrote the final answer 1.9N should it be 1.93N
I thought we were supposed to write in 2 sig figure :/ but I wrote 19/9.81 instead of 19/10

Last part :
I wrote
" For a body to be in equilibrium resultant sun of all forces should be zero so a force must act on A to make the resultant sun of all the forces zero. "

Is this correct because I didn't wrote
A force has to be exerted by A to ensure there is no net force of the rod
For question 3
I didn't showed a light SOURCE but I showed light rays coming from one side and labeled it with light.
And I did didn't mentioned that the smoke cell was closed by glass lid would that be fine?

For question 5:
Also tell that how a stationary wave was produced by the apparatus?

For the moment: perpendicular distance = 0 m...so moment = 0 Nm

 

[Umar Zain]

This thread is only for those who wish to check answers, and I may not have all the answers correct, but I'll try and edit this post and make sure all the correct answers have been uploaded for you all to check!


Question 1: Power base units : kgm^2 s^-3
C has no unit (easy to prove)
speed of wind: 9.44 m/s

Question 2: Accel-time graph
a= 3.5
so the graph is a flat line at a=3.5 upto t=2 seconds. then it becomes zero after 2s

Momentum time graph:
momentum is 16.4 Ns at t=2s
line has a constant gradient upto t=2s and then becomes flat.

Question 3: Moments
Tsin50= 22.8 N
Weight of O is approx 19N
Mass is 19/9.81
A force has to be exerted by A to ensure there is no net force of the rod

Question 4: Brownian Motion
Apparatus: Light source, closed GLASS box with smoke particles in side and a microscope to view the particles from top
What we notice: Smoke particles moving in random zig-zag manner.
Properties of gas we can conclude: Have high energy in the particles and move in a random manner OR gasses fill up the volume of the container.

Question 5: Stationary Waves
Wavelength= 0.8m
How stationary waves are formed:
Progressive waves generated travel to the other end and REFLECT back. The reflected waves then SUPERIMPOSE with the original progressive waves and create regions of max disp (anti-nodes) and min disp (nodes).
Nodes correctly labelled.
length of PQ is 1.2m
Stationary wave at t+5ms is a straight line drawn from P to Q

use frequency to find the time period T of the wave which is 0.02s
t+5ms= 0.025s which is 1/4 of the wave period.
therefore the wave is a flat line.

Question 6: Electricity
Power= 3200W
Current = 13.3 A
Charge= Current X Time
Electrons flowing per second: 8.34 X 10^19

Question 7: Radioactivity
Alpha particle is a helium nuclei so the WXYZ part was easy
Mass doesn't seem to be conserved because MASS ENERGY is conserved. The change in mass is converted to other forms of energy such as K.E in the particles or photons OR gamma radiation.
Radioactivity is spontaneous meaning it is not affected by external factors such as pressure.

That's about it. If you have confusions DO NOT PM me. Ask here and others MAY help you out.

For the momentum graphs, must we show all calculations?