OCR ADVANCING PHYSICS B G494 EXAM MONDAY 18th June

Reply 160

xiyangliu

2

Original post by :)!

I wan't sure either. Just looked it up. It was for gravitational potential so was JKg^-1. The other was Ns right?

Yeah. Got exact same

This was posted from The Student Room's iPhone/iPad App

Reply 161

Matt G

Original post by EricEdwardSelvaraj

For the last question my value was 0.2x10^10 i.e. 2x10^9 J. Some people here have got 3^9 J. Not sure if its because of rounding error. I remember my values for GPE being something like 2.1x10^10, and 1.9x10^10 for the other.

In the penultimate question, the arrow for the direction of gas is opposite to velocity, they were quite sneaky. Because I put the arrow in the direction of velocity, and changed it seconds before my paper was about to be taken.

Wasn't the rocket slowing down so you would shoot the gas in the direction of motion and from C of M, the rocket would slow down?

Reply 162

Rotravis

Did it ask for momentum or gpe units first?? I may have messed it up

Reply 163

Anthony Soprano

Original post by EricEdwardSelvaraj

For the last question my value was 0.2x10^10 i.e. 2x10^9 J. Some people here have got 3^9 J. Not sure if its because of rounding error. I remember my values for GPE being something like 2.1x10^10, and 1.9x10^10 for the other.

In the penultimate question, the arrow for the direction of gas is opposite to velocity, they were quite sneaky. Because I put the arrow in the direction of velocity, and changed it seconds before my paper was about to be taken.

I got 2x10^9 too.

Reply 164

littlemissmidget123

16

Original post by :)!

I wan't sure either. Just looked it up. It was for gravitational potential so was JKg^-1. The other was Ns right?

think i got that wrong.. yeah the second was Ns

so thats 2 marks ive lost.. otherwise i think it was good :smile:

Reply 165

Rotravis

Ah I think I may have written Ns onto the second line, then worked out the gpe units.. At least I hope so!

Reply 166

Revent

10

Fridge required use of ln(AB)=ln(A)+ln(B) I think that is unfair to those who don't do maths.

Reply 167

deejayy

1

Original post by Matt G

Wasn't the rocket slowing down so you would shoot the gas in the direction of motion and from C of M, the rocket would slow down?

That's what I did. The force was the opposite direction to velocity and the gas was shot out the same direction as velocity?

Reply 168

Oromis263

2

Partial Mark Scheme

Section A
1. J/kg
Ns

2. Energy stored = 18000J
Graph B

3. 28 micro seconds

4. Definition of decay constant: second tick (probability per unit time)
5. For the iterative table:
79, -17
62, -13
How would you improve the estimate for T_1/2. (Change delta T, or use larger N?)

6. 7.3J KE of brick
3.6J work done

7. -0.15 m/s velocity of combined blocks

8. Link the lines, can't remember but, f = fraction, epsilon = extra energy and kT = average thermal energy

9. Which factors A to E stay the same or blah
B
C

Another question in here was to draw the equipotential lines surrounding a star

Section B
10. a) v is the recession velocity of an object relative to Earth
r is the distance of said object from Earth

b) Show units H_0 have units s^-1

c) Draw a line of best fit, calculate gradient: 2.8x10^-18 was my H_0 (will be a range, as it was whatever you calculated your gradient to, from your line)

d) Evidence for Big Bang: If all moving from same point, then by reversing, it is possible to see that they all started from the same point, and are now moving outwards from there. This is the Big Bang.

e) Gives an estimate because 1/H_0 gives the time taken to reach a certain point, therefore the universe must be at least that old (if v has been constant)

f) Age of universe, 1.3x10^10 years

11. a) How many particles in fridge, 5.7x10^24 particles

b) Energy lost when cooled from 288K to 253K, 2800J

c) Link the behaviour of particles to the decreasing temperature to explain why the pressure dropped

d) Calculate the new pressure, 8.8x10^4 Pa

e) Work out epsilon, epsilon = 1.6x10^-19J

12. a) Calculate the spring constant 2.8x10^4 N/m

b) Calculate the frequency 3.4Hz

c) Explain why the system was damped. It is damped so that any oscillations that occur in the spring are reduced, as they are unwanted, and could cause danger to the rider. The damping dissipates the kinetic energy of the oscillations and prevents them from continuing

d) Extra bit here, forgotten, anyone remember?

13. a) Manipulate expressions of centripetal force = gravitational force

b) Show total energy, E = -GMm/2r

c) Draw the graph of E against r, for values of r greater than R

d) Draw an arrow downwards (opposing the motion) from the rocket

e) Draw an arrow upwards to show the motion of the gas particles

f) Calculate the work done from moving the satellite from height 1 to a lower height 2. 2.1x10^9 J, work done.

That's what I got. :smile:

Any corrections, just quote this post.

(edited 11 years ago)

Reply 169

Darkphilosopher

16

Hmm, for the particles in the fridge I got 8.6*10^24 :colonhash:

pV = nkT

n = pV/kT

Not sure where I went wrong there :frown:

Reply 170

Dhanu123

3

Original post by Oromis263

Partial Mark Scheme

Section A
1. J/kg
Ns

2. Energy stored = 18000J
Graph B

3. 28 micro seconds

4. Definition of decay constant: second tick (probability per unit time)
5. For the iterative table:
79, -17
62, -13
How would you improve the estimate for T_1/2. (Change delta T, or use larger N?)

6. 7.3J KE of brick
3.6J work done

7. -0.15 m/s velocity of combined blocks

8. Link the lines, can't remember but, f = fraction, epsilon = extra energy and kT = average thermal energy

9. Which factors A to E stay the same or blah
B
C

Another question in here was to draw the equipotential lines surrounding a star

Section B
10. a) v is the recession velocity of an object relative to Earth
r is the distance of said object from Earth

b) Show units H_0 have units s^-1

c) Draw a line of best fit, calculate gradient: 2.8x10^-18 was my H_0 (will be a range, as it was whatever you calculated your gradient to, from your line)

d) Evidence for Big Bang: If all moving from same point, then by reversing, it is possible to see that they all started from the same point, and are now moving outwards from there. This is the Big Bang.

e) Gives an estimate because 1/H_0 gives the time taken to reach a certain point, therefore the universe must be at least that old (if v has been constant)

f) Age of universe, 1.3x10^10 years

11. a) How many particles in fridge, 5.7x10^24 particles

b) Energy lost when cooled from 288K to 253K, 2800J

c) Link the behaviour of particles to the decreasing temperature to explain why the pressure dropped

d) Calculate the new pressure, 8.8x10^4 Pa

e) Work out epsilon, epsilon = 1.6x10^-19J

12. a) Calculate the spring constant 2.8x10^4 N/m

b) Calculate the frequency 3.4Hz

c) Explain why the system was damped. It is damped so that any oscillations that occur in the spring are reduced, as they are unwanted, and could cause danger to the rider. The damping dissipates the kinetic energy of the oscillations and prevents them from continuing

d) Extra bit here, forgotten, anyone remember?

13. a) Manipulate expressions of centripetal force = gravitational force

b) Show total energy, E = -GMm/2r

c) Draw the graph of E against r, for values of r greater than R

d) Draw an arrow downwards (opposing the motion) from the rocket

e) Draw an arrow upwards to show the motion of the gas particles

f) Calculate the work done from moving the satellite from height 1 to a lower height 2. 2.1x10^9 J, work done.

That's what I got. :smile:

Any corrections, just quote this post.

i got 3.5 Hz i think for the frequency, must have messed up the rounding somewhere.

I thought the epsilon fridge question was lovely, but really fiddly...

ended up with ln(2/500)/(1/288k - 1/253k) = 1.6 x 10^-19 :smile:

Reply 171

Oromis263

2

Original post by Darkphilosopher

Hmm, for the particles in the fridge I got 8.6*10^24 :colonhash:

pV = nkT

n = pV/kT

Not sure where I went wrong there :frown:

That's the correct formula, I'm not sure either. The values were:
p = 1x10^5
V = 0.23
k is the constant
T = 288

Do you agree in general with the rest? I wasn't too sure about the change to the equation to get a better half life measure. :smile:

Reply 172

Oromis263

2

Original post by Dhanu123

i got 3.5 Hz i think for the frequency, must have messed up the rounding somewhere.

I thought the epsilon fridge question was lovely, but really fiddly...

ended up with ln(2/500)/(1/288k - 1/253k) = 1.6 x 10^-19 :smile:

3.5 was right if you used the value for the spring constant given, my friend did that as well, I just carried my calculated result?

Reply 173

Dhanu123

3

Original post by Oromis263

3.5 was right if you used the value for the spring constant given, my friend did that as well, I just carried my calculated result?

ah yeah, thats that one. i remember :smile:

and for the T1/2 question, it was T1/2=gammaT1/2(0) right?

Reply 174

EricEdwardSelvaraj

Original post by Oromis263

Partial Mark Scheme

Section A
1. J/kg
Ns

2. Energy stored = 18000J
Graph B

3. 28 micro seconds

4. Definition of decay constant: second tick (probability per unit time)
5. For the iterative table:
79, -17
62, -13
How would you improve the estimate for T_1/2. (Change delta T, or use larger N?)

6. 7.3J KE of brick
3.6J work done

7. -0.15 m/s velocity of combined blocks

8. Link the lines, can't remember but, f = fraction, epsilon = extra energy and kT = average thermal energy

9. Which factors A to E stay the same or blah
B
C

Another question in here was to draw the equipotential lines surrounding a star

Section B
10. a) v is the recession velocity of an object relative to Earth
r is the distance of said object from Earth

b) Show units H_0 have units s^-1

c) Draw a line of best fit, calculate gradient: 2.8x10^-18 was my H_0 (will be a range, as it was whatever you calculated your gradient to, from your line)

d) Evidence for Big Bang: If all moving from same point, then by reversing, it is possible to see that they all started from the same point, and are now moving outwards from there. This is the Big Bang.

e) Gives an estimate because 1/H_0 gives the time taken to reach a certain point, therefore the universe must be at least that old (if v has been constant)

f) Age of universe, 1.3x10^10 years

11. a) How many particles in fridge, 5.7x10^24 particles

b) Energy lost when cooled from 288K to 253K, 2800J

c) Link the behaviour of particles to the decreasing temperature to explain why the pressure dropped

d) Calculate the new pressure, 8.8x10^4 Pa

e) Work out epsilon, epsilon = 1.6x10^-19J

12. a) Calculate the spring constant 2.8x10^4 N/m

b) Calculate the frequency 3.4Hz

c) Explain why the system was damped. It is damped so that any oscillations that occur in the spring are reduced, as they are unwanted, and could cause danger to the rider. The damping dissipates the kinetic energy of the oscillations and prevents them from continuing

d) Extra bit here, forgotten, anyone remember?

13. a) Manipulate expressions of centripetal force = gravitational force

b) Show total energy, E = -GMm/2r

c) Draw the graph of E against r, for values of r greater than R

d) Draw an arrow downwards (opposing the motion) from the rocket

e) Draw an arrow upwards to show the motion of the gas particles

f) Calculate the work done from moving the satellite from height 1 to a lower height 2. 2.1x10^9 J, work done.

That's what I got. :smile:

Any corrections, just quote this post.

Wow! my memory must be that of a goldfish compared to yours. As far as I can see, I have lost 7 marks - 3 from the fridge question, 1 from the section A graph question, 2 from 13e and 1 from 13c. Rest of it inc. values for H0 and 13f is same as ones I got. For 9, I cant remember which is which but I said total energy is constant, and acceleration.

We also had a question drawing lines between f, kt, etc to fraction of molecules, average thermal energy.

Reply 175

Anthony Soprano

Original post by Oromis263

Partial Mark Scheme

Section A
1. J/kg
Ns

2. Energy stored = 18000J
Graph B

3. 28 micro seconds

4. Definition of decay constant: second tick (probability per unit time)
5. For the iterative table:
79, -17
62, -13
How would you improve the estimate for T_1/2. (Change delta T, or use larger N?)

6. 7.3J KE of brick
3.6J work done

7. -0.15 m/s velocity of combined blocks

8. Link the lines, can't remember but, f = fraction, epsilon = extra energy and kT = average thermal energy

9. Which factors A to E stay the same or blah
B
C

Another question in here was to draw the equipotential lines surrounding a star

Section B
10. a) v is the recession velocity of an object relative to Earth
r is the distance of said object from Earth

b) Show units H_0 have units s^-1

c) Draw a line of best fit, calculate gradient: 2.8x10^-18 was my H_0 (will be a range, as it was whatever you calculated your gradient to, from your line)

d) Evidence for Big Bang: If all moving from same point, then by reversing, it is possible to see that they all started from the same point, and are now moving outwards from there. This is the Big Bang.

e) Gives an estimate because 1/H_0 gives the time taken to reach a certain point, therefore the universe must be at least that old (if v has been constant)

f) Age of universe, 1.3x10^10 years

11. a) How many particles in fridge, 5.7x10^24 particles

b) Energy lost when cooled from 288K to 253K, 2800J

c) Link the behaviour of particles to the decreasing temperature to explain why the pressure dropped

d) Calculate the new pressure, 8.8x10^4 Pa

e) Work out epsilon, epsilon = 1.6x10^-19J

12. a) Calculate the spring constant 2.8x10^4 N/m

b) Calculate the frequency 3.4Hz

c) Explain why the system was damped. It is damped so that any oscillations that occur in the spring are reduced, as they are unwanted, and could cause danger to the rider. The damping dissipates the kinetic energy of the oscillations and prevents them from continuing

d) Extra bit here, forgotten, anyone remember?

13. a) Manipulate expressions of centripetal force = gravitational force

b) Show total energy, E = -GMm/2r

c) Draw the graph of E against r, for values of r greater than R

d) Draw an arrow downwards (opposing the motion) from the rocket

e) Draw an arrow upwards to show the motion of the gas particles

f) Calculate the work done from moving the satellite from height 1 to a lower height 2. 2.1x10^9 J, work done.

That's what I got. :smile:

Any corrections, just quote this post.

YES! Practically same answers throughout, numerical answers at least.

For 13b) you make the denominators common for kinetic energy and then add the numerators together, GmM - 2GmM = -GmM or something like that.

Frequency i either go 3.00 or 3.50, not sure, probably rounding somewhere.

And for question 5 i put both smaller change in T and larger initial N.

Actually for the fridge one I also got 8.6x10^24 not 5.7, and when i subbed it back into the equation, p1v1/t1 = 79.9 and p2v2/t2= 80, which works, not sure about the 5.7 you got :/

(edited 11 years ago)

Reply 176

:)!

5

Are the grade boundaries likely to be the same as Jan?

Reply 177

EricEdwardSelvaraj

Original post by :)!

Are the grade boundaries likely to be the same as Jan?

It may be higher. :frown:

This paper was quite similar to the legacy papers. It did not exactly have many stretch and challenge questions apart from that infuriating fridge.

Personally I felt Jan 2012 was harder, as it had at least two major (3+ marks) questions which I struggled with.

Reply 178

xiyangliu

2

Question 12 c I didn't mention abt resonance. Would I lose any marks on that ??

This was posted from The Student Room's iPhone/iPad App

Reply 179

Dhanu123

3

Original post by xiyangliu

Question 12 c I didn't mention abt resonance. Would I lose any marks on that ??

This was posted from The Student Room's iPhone/iPad App

one of the key words was high amplitude i believe, so resonance would have helped in the sentence, then some people talked a KE dissipation instead, so i have no idea what the question was actually looking for

OCR ADVANCING PHYSICS B G494 EXAM MONDAY 18th June

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