# AQA PHYA4 ~ 13th June 2013 ~ A2 Physics Watch

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#1001

(Original post by

I meant that Ns-1 is a unit for impulse, and im sure answer A was Ns-1?

**Adamcfc**)I meant that Ns-1 is a unit for impulse, and im sure answer A was Ns-1?

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#1002

(Original post by

You would get the same dY/dX so its k cause you'd draw it from the zero point to the maximum value

**benethcheese**)You would get the same dY/dX so its k cause you'd draw it from the zero point to the maximum value

is max when , so:

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#1003

M/C in no particular order:

1)

2)

3)path of electron was

4)potential at mars was

5)maximum value of tension was

6)

7) capacitance graph question was

8)

9） ratio of y/d=

10) R earth

Mass of the earth is 81 x mass of the moon

Gravitational field strength on the earth = 9.8

Gravitational field strength on the moon = 1.8

g =GM/r^2.

9.8 = 81GM/re^2

1.8 = GM/rm^2

Re-arrange and you get re^2/rm^2 = ~

11)which one is incorrect: when

12) which one is incorrect:

13)moving

14)rotating coil was

15) Capacitance value of 0.02F for one question forgot which was, answer choice was

16) units of impulse =

17) momentum question when the 2 trolleys collided:

18) negative ion moving through 2 plates, the lower earthed the upper at + 50V, the

19)Something about max angular speed when the friction on a turntable of radius r is =

SECTION B IS COMPLETE

1a)define shm:

acceleration was

frequency of pendulum =

time for oscilations to be in phase again =

after 1 oscilation - difference on 0.1s

after 2 oscillations - difference of 0.2s....

after 19 oscillations difference of 1.9 seconds

so on the 19th osciation of the 1.9s pendulum, the 2s pendulum will arrive 1.9s after it, so on the 20th oscillation of the 1.9s pendulum they are in phase. again, on the 19th oscillation of the 2s pendulum they will be in phase.

19 x 2 = 38s

20 x 1.9 = 38s

TOTAL = 12

2) voltage =

b) i think this was the capacity was increase from X to Y.time taken for the spark to be produced after the last discharge?

then Q=CV, then Q/Current = time was ~

c)

d)

TOTAL = 7

1. gravity always attractive

2. electric attractive/repulsive

3. both follow inverse square for Force

4. both follow inverse for potential

5. gravity uses mass

6. electric uses charge

7. only electric fields can be shielded

8. only electric fields depend on medium between charges

9. gradient of potential vs distance graph gives field strength

10. potential definition for both revolves around bringing a mass/charge from infinity to a certain point in a field and is zero at infinity

TOTAL = 6

b)

b) prove momentum is proportional to radius=

the speed of particle=

c)time taken for partile to go through 1 dee =

d)show the time taken is independent of radius =

kinetic energy im MEV =

TOTAL = 15

5)

angle for max emf =

angle for max flux linkage =

gradient of graph =

drawing a graph (2)

peak voltage (3)

calculate flux density =

TOTAL= 10

1)

**t root2**, <--- it was something to do with the time period of a mass on two springs (if I remember right..)2)

**460 and current its greater that 0.26**,3)path of electron was

**A the arrow pointing upwards**,4)potential at mars was

**-13,**5)maximum value of tension was

**24**6)

**K.E: P>Q, G.P.E: Q<P**7) capacitance graph question was

**D**,8)

**fe>fs>fm**I just thought that would mean something would be more attracted to the sun over the moon so it would leave the moons orbit? many of us also got:**fe>fm>fs**9） ratio of y/d=

**1/3**–**I got 2/3 :/**10) R earth

**^2**/Rmoon**^2**=**14**----- >As I remember the question:Mass of the earth is 81 x mass of the moon

Gravitational field strength on the earth = 9.8

Gravitational field strength on the moon = 1.8

g =GM/r^2.

9.8 = 81GM/re^2

1.8 = GM/rm^2

Re-arrange and you get re^2/rm^2 = ~

**14.88**11)which one is incorrect: when

**spring is compressed &suspended,it has minimum PE**12) which one is incorrect:

**change of momentum=zero**13)moving

**horizontally,Blv …**14)rotating coil was

**A**q14 from http://papers.xtremepapers.com/AQA/P...W-QP-JAN03.pdf MS - http://papers.xtremepapers.com/AQA/P...W-MS-JAN03.pdf15) Capacitance value of 0.02F for one question forgot which was, answer choice was

**B**16) units of impulse =

**kgms-1**17) momentum question when the 2 trolleys collided:

**12000Ns**18) negative ion moving through 2 plates, the lower earthed the upper at + 50V, the

**ion moved upwards**towards the positive plate19)Something about max angular speed when the friction on a turntable of radius r is =

**mg/2****6 MORE MULTIPLE CHOICE QUESTIONS THEN DONE!**SECTION B IS COMPLETE

1a)define shm:

**acceleration is proportinal to displacement, and acceleration acts toward equilibrium**(2)acceleration was

**-0.4**frequency of pendulum =

**0.503**3s.f (3)time for oscilations to be in phase again =

**38**(3) -- if you think about it,after 1 oscilation - difference on 0.1s

after 2 oscillations - difference of 0.2s....

after 19 oscillations difference of 1.9 seconds

so on the 19th osciation of the 1.9s pendulum, the 2s pendulum will arrive 1.9s after it, so on the 20th oscillation of the 1.9s pendulum they are in phase. again, on the 19th oscillation of the 2s pendulum they will be in phase.

19 x 2 = 38s

20 x 1.9 = 38s

TOTAL = 12

2) voltage =

**30,000**(1)b) i think this was the capacity was increase from X to Y.time taken for the spark to be produced after the last discharge?

then Q=CV, then Q/Current = time was ~

**3.46s**c)

**time taken for discharge will increase because time constant increases**(2)d)

**flash is brighter because more energy stored**(2)TOTAL = 7

**4**) 6 marker on fields1. gravity always attractive

2. electric attractive/repulsive

3. both follow inverse square for Force

4. both follow inverse for potential

5. gravity uses mass

6. electric uses charge

7. only electric fields can be shielded

8. only electric fields depend on medium between charges

9. gradient of potential vs distance graph gives field strength

10. potential definition for both revolves around bringing a mass/charge from infinity to a certain point in a field and is zero at infinity

TOTAL = 6

**3**) 2 conditions when no force is exerted on the particle (2)**field is parallel to velocity**

particle is stationaryparticle is stationary

b)

**out of the plane of the paper**b) prove momentum is proportional to radius=

**mv^2/r = BQv , mv = BQr --> mv = kr**the speed of particle=

**8.7x107**c)time taken for partile to go through 1 dee =

**~6.8x10^-8**d)show the time taken is independent of radius =

**2pim/bq**(3)kinetic energy im MEV =

**2.44**(3)TOTAL = 15

5)

**1500**revs per minute (2) [I'm sorry MSI_10 :'( ]angle for max emf =

**60 degrees**-- this is at 90 degrees to the plane as emf = BANw sin(wt) therefore max emf is when sin(wt) =1, there for wt (which is the angle) = 90, 90-30 = 60 degreesangle for max flux linkage =

**5pi/6 = 2.62 radians**-- this is at 0 degrees = 180 degrees, and N(PHI) = BAN cos(THETA), so max is when cos(THETA) = 1 so theta = 180, 180-39 = 150 degrees = 5pi/6gradient of graph =

**emf**(1)drawing a graph (2)

**Positive Sine graph**peak voltage (3)

**86.4V**http://www.thestudentroom.co.uk/show...6#post43151006 THANK YOU SO MUCH QWERTISH!calculate flux density =

**0.26**(2)TOTAL= 10

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#1005

(Original post by

Why am I the only one who got 0.27 for the last one????

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**cooldudeman**)Why am I the only one who got 0.27 for the last one????

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Oh I thought you said 'Am I the only one...' now why :P

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#1006

(Original post by

18) negative ion moving through 2 plates, the lower earthed the upper at + 50V, the

**MisterE1**)18) negative ion moving through 2 plates, the lower earthed the upper at + 50V, the

**ion moved downwards**towards the earthed plate (answer B)The E-field is directed downward, q is negative, thus the force acting on it is directed upward.

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#1007

(Original post by

No.

The E-field is directed downward, q is negative, thus the force acting on it is directed upward.

**FO12DY**)No.

The E-field is directed downward, q is negative, thus the force acting on it is directed upward.

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#1008

**FO12DY**)

No.

The E-field is directed downward, q is negative, thus the force acting on it is directed upward.

(Original post by

I know it went upwards to the positive but I dont get how its 25V in the middle or something

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**cooldudeman**)I know it went upwards to the positive but I dont get how its 25V in the middle or something

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http://papers.xtremepapers.com/AQA/P...W-QP-JAN03.pdf

http://papers.xtremepapers.com/AQA/P...W-MS-JAN03.pdf

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#1009

(Original post by

No, you draw a tangent at any point where the flux linkage graph crosses the x-axis. You don't get the same value from dy/dx:

is max when , so:

**Qwertish**)No, you draw a tangent at any point where the flux linkage graph crosses the x-axis. You don't get the same value from dy/dx:

is max when , so:

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#1010

(Original post by

It's question 13 on here. The answer is B, downwards

http://papers.xtremepapers.com/AQA/P...W-QP-JAN03.pdf

http://papers.xtremepapers.com/AQA/P...W-MS-JAN03.pdf

**jonnyb123**)It's question 13 on here. The answer is B, downwards

http://papers.xtremepapers.com/AQA/P...W-QP-JAN03.pdf

http://papers.xtremepapers.com/AQA/P...W-MS-JAN03.pdf

But I was talking about the negative ion question. It goes to the +plate, not down to earth as MisterE1 said.

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#1011

(Original post by

So are you saying 86 is the correct ans or not? ?

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**cooldudeman**)So are you saying 86 is the correct ans or not? ?

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#1012

**FO12DY**)

No.

The E-field is directed downward, q is negative, thus the force acting on it is directed upward.

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#1013

**cooldudeman**)

I know it went upwards to the positive but I dont get how its 25V in the middle or something

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The air creates a potential divider, where the distances between the point under test and each plate d1, d2 are effectively resistors, R1, R2.

So the pd (50-0=50) is divided by the resistors 50*R2/(R1+R2).

As it's in the middle for this question, d1 = d2, R1 = R2 => V = 50/2 = 25.

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#1014

(Original post by

Yup. That's right.

But I was talking about the negative ion question. It goes to the +plate, not down to earth as MisterE1 said.

**FO12DY**)Yup. That's right.

But I was talking about the negative ion question. It goes to the +plate, not down to earth as MisterE1 said.

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#1015

(Original post by

well spotted! thanks

**MisterE1**)well spotted! thanks

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#1016

(Original post by

Correct

**Qwertish**)Correct

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#1017

(Original post by

So you get 86 if you do it the max gradient way too?

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**cooldudeman**)So you get 86 if you do it the max gradient way too?

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#1018

guys, I think the emf graph is supposed to be minus sine

(assuming that the flux graph was minus cosine)

(assuming that the flux graph was minus cosine)

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#1019

(Original post by

For the peak emf I calculated the gradient at 0 flux linkage and got 100V.. Is that right?

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**Gernick**)For the peak emf I calculated the gradient at 0 flux linkage and got 100V.. Is that right?

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#1020

(Original post by

guys, I think the emf graph is supposed to be minus sine

(assuming that the flux graph was minus cosine)

**Jack93o**)guys, I think the emf graph is supposed to be minus sine

(assuming that the flux graph was minus cosine)

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