May 2015- Physics Paper 1 and Paper 2

[Hassan76]

Frequency in Q4 is supposed to be calculated by using the path difference for constructive interference, I think, i.e. even multiples of half wavelengths, given the wavelength and probably dividing it by the speed to get the frequency values. 

 

But I couldn't figure it out and didn't have time so I simply just did v/lambda which is wrong

Btw it was destructive

[Megamind]

Are you sure? They asked for the maxima's I think. 

[Hassan76]

Anyone SL TZ1? I found paper 1 really different and a lot harder than previous exams but paper 2 was a lot easier... I chose question 4.

I was time zone 1 SL. Honestly there was a lot of guessing going on there. On paper 1 I mean come on... where were the classic is this a fundamental or derived unit questions... or scalar vs vector quantity... A lot of the questions we did were in higher too, my classmates who are all higher told me (24 hours later 13:00 GMT - just to clarify) that they too had many of our questions.

As for Paper 2 did you do the environmental that was like an amalgamation of nuclear and wind energy? -Btw that first uncertainty question on the graph was really tough with R and finding the uncertainty of V. Data analysis was far harder this year I felt, the rest was so so. Ugh and that 4 point ice cube question so annoying...

Ikr! The paper one had some really obscure questions that I hadn't seen before... especially in fields and magnetism...

For paper 2 the data analysis was tough but at least it was short.... so I'm praying for the markbands

Ya I did the environmental question.. it wasnt too bad so I was happy with that. What option did u choose?

I too did the environmental question. BTW did you find 1500 GW for your answer for power production of wind?? I am as we speak revising for my options modules because I haven't revised those yet!! We do Quantum and Astrophysics, ugh so much to do, so much little time to do it in!! For that uncertainty question in the data analysis - there has been much debate amongst my classmates. I thought that since R was the volume in the cylinder after 100s then the uncertainty of R must have included the uncertainty of s, so I just minused the uncertainty of s from R to find the uncertainty of V... what did you do. Also on the environmental option the first question did you interpret it that it required us to choose between oil or nuclear or just say why we needed a 2nd power production source?

Ya... For the first question I interpreted that it meant what conditions the island needed to have to be able to harness those energy forms... like it had to have enough sunlight to heat the air to produce wind currents and it had to have accessible ports to allow the imports of nuclear and fossil fuels.. all of my classmates however, put different things... I think the question itself was very weirdly worded and up to interpretation. For the wind energy one I also got 1500 GW, but it asked for the energy produced per year, so I multiplied it by the number of seconds in a year. For the first question I never thought about it like that. I interpreted it as if the uncertainty was not included, so I said that the percent uncertainty was 6%, but now that I think of it, you're probably right. For the paper 1, do you remember the question with the particle that has a mass and a charge? What fields affect it? I knew that the electric and gravitational fields play a role, but does the magnetic field have any force on the particle?

It was c, twice the mass and half the speed, r is given by mv/bq

Edited May 9, 2015 by Hassan76

[Hassan76]

The derivation was tricky but simple once you got the principle underlying. The pendulum completes a half oscillation with its full length L therefore 

T = 0.5*2pi*Sq.root (l/g) = (pi/Sq.root g) * Sq. root of L . 

 

The pendulum completes another half oscillation with length X, therefore

T = 0.5*2pi*Sq.root (x/g) = (pi/Sq.root g) * Sq. root of X . 

 

 Therefore total time period = T = sum of both = (pi/Sq.root g) * (Sq. root X + Sq. root L) 

 

(Since the pendulum completes a quarter swing in full length L, then a quarter in the same direction with length X, then comes back a quarter period with swing X and then completes the last quarter of the period in full length L)

Your working gives 2 pi

[Megamind]

How? 

 

0.5*2 makes each time period 1 pi over here. 

 

When you add the two individual time periods, you take (pi/Sq.root g) common giving (pi/sq.root g) * (Sq. root X + Sq. root L) 

[Hassan76]

In the data analysis question, I got my slope around 1 and the y intercept aro0und 0.97. Anyone else? Also, when you took out the x intercept by equation y=mx + c to zero, did anyone find the value of x weird? Because I got some -0.98 or something and by observing and extrapolating the graph mentally to the minus x axis, it didn't look more than a -0.10. Did anyone get L as 0.93??

 

In paper 1 (Tz2) there was a question about green light being emitted from two point sources which was just NOT resolved. So the question asked how to resolve it and there were two plausible options: use red light (higher wavelength so bigger theta) and use a circular aperture (again bigger theta since 1.22 is there instead of 1). What'd you guys write? I chose red light. 

 

Ossih, what did you write for the possible binary states? 15 or 16? 

 

I had no idea what the "s" in capacitance meant, so I had to skip that question . I mean I knew it was the Farad but I forgot the definition :/ and in all my years of Physics, I have never seen a freaking s as a fundamental unit . Randomnly ticked something and probably got it wrong. 

 

In Paper 2 (tz2), for question 6, everyone found the gravitational field strength as Del V/ Del T right? And therefore from the calculation the rocket cannot escape without further engine use. 

 

Sorry about the blast of questions in your face, I'm just too excited to know everybody's else's answers . 

Also, any other Paper 1 questions anyone found challenging? I keep forgetting :/

I gave the same answers as you for data analysis and green light emitted, also 16  is the correct answer, then doesnt "s" stand simply for second? anyway i got that wrong haha and I found the grav strength from two mechanics formulas   s = (v+t)2 * t and  v^2 =  u^2 + 2gs

I thought that s could stand for second, but then I simply remembered that capacitance involved charge, I didn't remember the whole formula :/ So I disregarded it :/ 

In the data analysis question, I got my slope around 1 and the y intercept aro0und 0.97. Anyone else? Also, when you took out the x intercept by equation y=mx + c to zero, did anyone find the value of x weird? Because I got some -0.98 or something and by observing and extrapolating the graph mentally to the minus x axis, it didn't look more than a -0.10. Did anyone get L as 0.93??

 

In paper 1 (Tz2) there was a question about green light being emitted from two point sources which was just NOT resolved. So the question asked how to resolve it and there were two plausible options: use red light (higher wavelength so bigger theta) and use a circular aperture (again bigger theta since 1.22 is there instead of 1). What'd you guys write? I chose red light. 

 

Ossih, what did you write for the possible binary states? 15 or 16? 

 

I had no idea what the "s" in capacitance meant, so I had to skip that question . I mean I knew it was the Farad but I forgot the definition :/ and in all my years of Physics, I have never seen a freaking s as a fundamental unit . Randomnly ticked something and probably got it wrong. 

 

In Paper 2 (tz2), for question 6, everyone found the gravitational field strength as Del V/ Del T right? And therefore from the calculation the rocket cannot escape without further engine use. 

 

Sorry about the blast of questions in your face, I'm just too excited to know everybody's else's answers . 

Also, any other Paper 1 questions anyone found challenging? I keep forgetting :/

 

I put 16 binary states! 

 

Also for the one with finding the induced emf, i started with NBA cos theta but it struck me that it's wrong.

 

The reason is, they ask for the induced emf JUST when the coil is about to completely enter. And so you'd so induced emf = ∆flux/∆t (emf is not NBA cos theta, that's flux ) and you'd find ∆t using suvat equations for free fall. The problem is, that's not the instantaneous change, that's average, that's not specific to when the coil just enters the field.

 

Instead, I did this. I used e = BLv, i said L was the length of one side (cause only one side is moving perpendicular to the field) and v = √2gh because its falling freely, where h is the length of the side. This made sense to me cause thats the instantaneous velocity at the time it just almost completely enters the field! What do you think?

 

I guess it makes sense . 2-3 marks gone ughhh.

Coulomb is Ampere Second, and power involves s to the power of -3

[FadyR]

Guys what about the percentage of use of renewable energy, I chose 30%

10%

[Hassan76]

SL TZ2 Here!

We reallly need a separate page for SL and HL.. anyways part A for the component parallel to the plane (guy riding the bicycle) was it simply mg sin x? and then mg cos x for the second question? or did I mess up? 

Also, did anyone take number 5 in section B? the last question in the electrical currents part where they asked for the power. It was worth 3 marks but the questions before it required to find the current and gave the voltage and for that question all I did was p=vi, input the given data and get P.. did I do it wrong? was there calculation required? Where are all those 3 marks! Im freaking out! 

For the data analysis, I got slope of 0.82 or something like that, for the y intercept I just extrapolated the graph and found the point which was 1 (I think). and to solve for the x intercept I just used the 0=0.82x+1 which gave me some negative number.. anyone to confirm? 

and for paper one! what did you guys put for the Albedo question /Snow/Ocean/Desert.. and what about the elevator and the weight one?

 

I did question 5 in Section B. I got the current to be something like 0.4545, but I wasnt sure if that was right for the ii part. For the last part, I think I did something very similar. But what values did u get?

 

For the elevator, i think it was (mg - ma). And for the bicycle it was sin first and then cos. 

 

I got a negative number as well. I got the slope to 1.05 and the intercept to be 0.96. 

 

What did u get for the displacement of the bicycle once he braked? I am freaking out about that question.

 

Albedo one, I did desert, ocean and then snow.

 

But for the resistance question? What type of graph did u draw for the resistance againt diameter? I drew a curve line going through the point, but I wasnt sure :/

Resistance is proportional to 1/d squared, albedo is greatest for snow lowest for ocean

[Hassan76]

Because it would then be a circuit, so current will flow. According to Lenz's law, the force created by that current will oppose the force that created it, which was the force downwards. So suddenly, there will be a force upwards which slows it down.

Isn't it related to the increased circumference and constant velocity so more time ?

[Hassan76]

Because it would then be a circuit, so current will flow. According to Lenz's law, the force created by that current will oppose the force that created it, which was the force downwards. So suddenly, there will be a force upwards which slows it down.

Isn't it related to the increased circumference and constant velocity so more time ?

But I prefer your answer, Sofia Edited May 9, 2015 by Hassan76

[aa557]

Someone doing SL?

Me, TZ1

Yes I did tz1 too. How do you think it was?

[Guest]

Paper 1 for me was horrible, I did really bad on that one. Paper 2 was a bit easier, Section A had a couple of tricky questions, but in general wasnt too difficult. Section B i chose question 4, with nuclear and climate questions, again just a couple of hard ones in paper 2.

[RandomIBStudent]

 

 

 

In the data analysis question, I got my slope around 1 and the y intercept aro0und 0.97. Anyone else? Also, when you took out the x intercept by equation y=mx + c to zero, did anyone find the value of x weird? Because I got some -0.98 or something and by observing and extrapolating the graph mentally to the minus x axis, it didn't look more than a -0.10. Did anyone get L as 0.93??

 

In paper 1 (Tz2) there was a question about green light being emitted from two point sources which was just NOT resolved. So the question asked how to resolve it and there were two plausible options: use red light (higher wavelength so bigger theta) and use a circular aperture (again bigger theta since 1.22 is there instead of 1). What'd you guys write? I chose red light. 

 

Ossih, what did you write for the possible binary states? 15 or 16? 

 

I had no idea what the "s" in capacitance meant, so I had to skip that question . I mean I knew it was the Farad but I forgot the definition :/ and in all my years of Physics, I have never seen a freaking s as a fundamental unit . Randomnly ticked something and probably got it wrong. 

 

In Paper 2 (tz2), for question 6, everyone found the gravitational field strength as Del V/ Del T right? And therefore from the calculation the rocket cannot escape without further engine use. 

 

Sorry about the blast of questions in your face, I'm just too excited to know everybody's else's answers . 

Also, any other Paper 1 questions anyone found challenging? I keep forgetting :/

 

That paper 1 question was about expressing capacitance in base units, which would be: charge (C = A s) / voltage (V = J / C) => charge² (A² s²) / energy (J) => A² s² / N m => A² s² / (kg m² / s²) => A² s⁴ / kg m²

Simply, knowing that there is A^2 and kg leads to a às the correct answer without even looking to seconds

Guys what about paper 1, tz2,

 

 

Hassan, do you remember the answer for the last MCQ in P1? The one on quantum efficiency? You remember the option you ticked there? :/

 

Also what was your answer for the one on green light sources? 

Guys what about the percentage of use of renewable energy, I chose 30%

 

 

Me too, it was a total guess though 10 was too less and 50 too much

 

 

I chose 30% too. But apparently I checked my notes and it was 13%, so closer to 10% than 30%... Probably got it wrong :x

[Hassan76]

Sorry guys, can't remember. Was q9 the one of momentum and cycle with Pressure- Volume (im hl tz2). Getting quite confused

 

I think Q7 was the one with SHM and Thermal and Q8 was the one with momentum and Digital Technology.

1-data analysis

2- binding energy

3- evaporation

4-waves

5- emf. If you notice, these are the same questions in m14 tz2 section A except that 2 was thermal and 3 was binding energy

6- energy and mechanics HL

7- SHM and thermodynamics

8-momentum and digital technology

9-electric currents and Quantum physics

In the data analysis question, I got my slope around 1 and the y intercept aro0und 0.97. Anyone else? Also, when you took out the x intercept by equation y=mx + c to zero, did anyone find the value of x weird? Because I got some -0.98 or something and by observing and extrapolating the graph mentally to the minus x axis, it didn't look more than a -0.10. Did anyone get L as 0.93??

 

In paper 1 (Tz2) there was a question about green light being emitted from two point sources which was just NOT resolved. So the question asked how to resolve it and there were two plausible options: use red light (higher wavelength so bigger theta) and use a circular aperture (again bigger theta since 1.22 is there instead of 1). What'd you guys write? I chose red light. 

 

Ossih, what did you write for the possible binary states? 15 or 16? 

 

I had no idea what the "s" in capacitance meant, so I had to skip that question . I mean I knew it was the Farad but I forgot the definition :/ and in all my years of Physics, I have never seen a freaking s as a fundamental unit . Randomnly ticked something and probably got it wrong. 

 

In Paper 2 (tz2), for question 6, everyone found the gravitational field strength as Del V/ Del T right? And therefore from the calculation the rocket cannot escape without further engine use. 

 

Sorry about the blast of questions in your face, I'm just too excited to know everybody's else's answers . 

Also, any other Paper 1 questions anyone found challenging? I keep forgetting :/

 

That paper 1 question was about expressing capacitance in base units, which would be: charge (C = A s) / voltage (V = J / C) => charge² (A² s²) / energy (J) => A² s² / N m => A² s² / (kg m² / s²) => A² s⁴ / kg m²

Simply, knowing that there is A^2 and kg leads to a às the correct answer without even looking to seconds

Guys what about paper 1, tz2,

 

Hassan, do you remember the answer for the last MCQ in P1? The one on quantum efficiency? You remember the option you ticked there? :/

 

Also what was your answer for the one on green light sources? 

Guys what about the percentage of use of renewable energy, I chose 30%

 

 

Me too, it was a total guess though 10 was too less and 50 too much

 

I chose 30% too. But apparently I checked my notes and it was 13%, so closer to 10% than 30%... Probably got it wrong :x

Maybe it is increasing with time, remember IB questions are always tricky

[Hassan76]

I wish that the teachers comment on the 38th question in p1 and that it is discounted, I am really angry because I did it 8 and it was in Oxford study guide, this is rote memorization not physics

[Hassan76]

In the data analysis question, I got my slope around 1 and the y intercept aro0und 0.97. Anyone else? Also, when you took out the x intercept by equation y=mx + c to zero, did anyone find the value of x weird? Because I got some -0.98 or something and by observing and extrapolating the graph mentally to the minus x axis, it didn't look more than a -0.10. Did anyone get L as 0.93??

 

In paper 1 (Tz2) there was a question about green light being emitted from two point sources which was just NOT resolved. So the question asked how to resolve it and there were two plausible options: use red light (higher wavelength so bigger theta) and use a circular aperture (again bigger theta since 1.22 is there instead of 1). What'd you guys write? I chose red light. 

 

Ossih, what did you write for the possible binary states? 15 or 16? 

 

I had no idea what the "s" in capacitance meant, so I had to skip that question . I mean I knew it was the Farad but I forgot the definition :/ and in all my years of Physics, I have never seen a freaking s as a fundamental unit . Randomnly ticked something and probably got it wrong. 

 

In Paper 2 (tz2), for question 6, everyone found the gravitational field strength as Del V/ Del T right? And therefore from the calculation the rocket cannot escape without further engine use. 

 

Sorry about the blast of questions in your face, I'm just too excited to know everybody's else's answers . 

Also, any other Paper 1 questions anyone found challenging? I keep forgetting :/

 

I put 16 binary states! 

 

Also for the one with finding the induced emf, i started with NBA cos theta but it struck me that it's wrong.

 

The reason is, they ask for the induced emf JUST when the coil is about to completely enter. And so you'd so induced emf = ∆flux/∆t (emf is not NBA cos theta, that's flux ) and you'd find ∆t using suvat equations for free fall. The problem is, that's not the instantaneous change, that's average, that's not specific to when the coil just enters the field.

 

Instead, I did this. I used e = BLv, i said L was the length of one side (cause only one side is moving perpendicular to the field) and v = √2gh because its falling freely, where h is the length of the side. This made sense to me cause thats the instantaneous velocity at the time it just almost completely enters the field! What do you think?

Ossih, what was the answer to the question about frequency in section A ? And please tell me how you got the reading on the voltmeter in q 9

[Hassan76]

The tricks in p2 tz2 were clear except for q5 /emf, in q 9 you had to calculate the area from the radius not diameter to get the resistance, or divide by 4, the mass in the nuclear question was given in m g so 10^-6 kg, and did you know guys that the question about temperature and heat you could have got a mark for saying that t is measured in kelvin and heat in joules, as in N11 hp2 q2, and unfortunately, for tz2 , - I am not saying this to bother anyone, but those who want a 7 need to do very well on paper 3 as paper 2 will have high boundaries /about 68 or 69 for the 7, paper 1 will have 28-31 , and I think it should be less than 31, the problem is that paper 1 had very hard and very easy questions, so IB could look at it as easy and raise the boundaries.

[Hassan76]

Guys what about the potential divider question in p1 , and the projectile, and the equipotential, equiptential was for same masses and same charges, projectile was vertically upward since initial vertical v is not 0, as some times when it is launched horizontally initial v in the vertical component is 0 as in May tz1 hp2, potential divider it had a 0 but don't know at the beginning or at the end, electron was accelerating at a decreasing rate and speed was increasing, and this was related to the question about the average speed in 9 in paper 2. And it was in m13 hp2 tz1, equations of motion, constant net force and fixed mass so that a is constant, graph always accelerating since the slope the graph is never parallel to the x axis but v is 0 at an instant so it is not always moving, first question is 3 as 10^_-27 and 10^ -30 , and it is not unfamiliar, the girl's gain in me is 600 areas of the three triangles, entropy of the universe increasing for the melting ice, for isothermal work is greater than adiabatic and delta u is 0, for the gravitational potential it is - 2GM / R +r since it is a scalar, if the question was asking what is the gravitational field strength which is a vector it would be 0, emissivity different temperature same, greenhouses gases was last one, resolution was violet, circle was frequency constantly varying, wave velocity to the right was A, when the slope is increasing, u tube I think it is d as initial displacement doesn't mean no 0 initial velocity and the liquid's motion is damped but I chose a as it is oscillating so v is positive and negative, for the momentum the last one was not valid, for the electric field strength it was b , closest to - 20 , for the maximum power in one of the resistors it is VI not 2VI, for the artificial transmutation it was easy, c I think as I do not remember the choices, for the kinetic model assumption it is elasticity of collisions, for the equilibrium temperature between water and paraffin it is 60 degrees, for the centripetal acceleration it was very easy, for the higher frequency couloir a higher photo current and a larger (more negative) stopping potential, for the evidence of nuclear energy levels it is the discrete nature of alpha and gamma, for the power of the wave it is p over 2, for the wavelenth of 4 V it was half the de broglie wavelenth, for the mass spectrometer it is half v and twice the mass, for the resistance the ratio was 8:1, as d/2 will multiply the area by 0.25, for the alpha particles deflection it is maximum for n at theta equal 0 and minimum when theta is near 170, for the frequency and the halved le th it is still 500 Hz as th the closed end will give wavelenth = 4 * L/2 , which is still 2 L, for the coil I chose the first one, positive sine for the current, for the direction of the force I chose A,

Concerning the question that asked what is not possible is momentum: momentum is given by h/ lambda, electron box model states that the wavelengths can be 2L/n where n is an integer, so 2l, l, 2/3, L/2, 2l/5' 2L/6 etc......,

For the sl, the question about gravitational field strength it is 20,

What do you guys think, plz share with me

Edited May 10, 2015 by Hassan76

[Hassan76]

TZ2 here.

 

I thought paper 2 was a gift from satan, I don't know how you guys found it easy. I chose questions 7 and 8.

Paper 1 was so-so. Did anyone get a ton of A's in paper 1?

 

Or is it just me 

 

I'm really hoping paper 3 won't be too hard.

 Q7 was a gift

How did you find question 7?

[Hassan76]

Guys can someone from tz2 remind me what were the choices in the question about the momentum ? Because I feel that I've made a silly mistake. Thanks