# A Level OCR Physics A Paper 1 2019 Unofficial Markscheme

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#3

MP choice

16) YM question

17) Graph of v against t question

18) Braking distance/6 marker

So braking: 38-9=29

19) SHM

20) Moments question

21) Thermal/ Kinetic theory

22) Luminosity 6 marker

23) Keplers 3rd law

24) Graviational force/ planets question

**1.A****2.B****3.D****4.D****5.C****6.D****7.A****8.B****9.C****10.C****11.D****12.D****13.A****14.D****15.B**16) YM question

**UTS - Maximum stress before the material breaks****Force constant 500000 Nm-1**17) Graph of v against t question

**Acceleration=1.3****Resultant force= F=ma (cant remember mass)****Drag force= 0.102****Resultant force= larger as mass=larger so weight component is larger for same amount of drag at 0.5 ms^-1****The ball with sand in had a higher terminal velocity than the hollow ball due to the fact that at terminal velocity drag=weight so if the weight is higher so is the drag. Since drag is proportional to speed the sand ball therefore had a higher terminal velocity.**18) Braking distance/6 marker

**Find thinking distance then take away from stopping distance to find braking distance. Use initial velocity, final velocity and braking to find deceleration(?)****Thinking distance: 18x0.5= 9m**

So braking: 38-9=29

**s=29 u=18 v=0 therefore a=-5.6 (2sf)****6 marker: Talked about having a ball launcher which varies the force it launches the ball at, light gate to get an initial velocity, measuring the distance travelled with a ruler, repeats and then plotting a graph of v^2 against x or somehting and using the gradient to calculate F**19) SHM

**Amplitude 0.079**20) Moments question

**14kg**21) Thermal/ Kinetic theory

**For the values of specific heat capacity, i put solid had a larger one because it had a smaller gradient and liquid had smaller specific heat capacity as it was more steep. Coz gradient was proportial to 1/c****RMS 672****Internal Energy 8500J**22) Luminosity 6 marker

**Work out the average temp for both planets, and the planet which was 9 x 10^x m away was habitable for life because it had a temp of ~190k. I concluded that the closer planet wasn’t habitable for life because it’s temp was ~450k. Use Stefan's law equation to show that’s the radius of the star was less than the radius of the sun.****Did the first part differently, found the constant using Earth and Sun data, Then used TRAPPIST-1 data and kept Temperature as 290K (as this is habitable) and solved for r. Found r to be about 3x10^9 m which was within range of planets from TRAPPIST-1 so therefore there was a chance of life. Or finding the exact distance wasn't really needed, as 290K is not the only habitable temp, the idea was that it could sustain liquid water (ignoring ammonia based life)**23) Keplers 3rd law

**Put values into formula**24) Graviational force/ planets question

**Mass would be larger as there not just stars in a galaxy there are also planets dark matter etc.**
Last edited by B0redBrioche; 2 years ago

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#6

yh and it rms speed of 650 or something

(Original post by

i got 8500J for the internal energy of 1.3 moles of gas at 250 celcius

**jason0597**)i got 8500J for the internal energy of 1.3 moles of gas at 250 celcius

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#8

(Original post by

13.something kg for the mass of the wooden thing

**Labib98**)13.something kg for the mass of the wooden thing

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#9

for the luminosity 6 marker I worked out the average temp for both planets, and the planet which was 9 x 10^x m away was habitable for life because it had a temp of ~190k. I concluded that the closer planet wasn’t habitable for life because it’s temp was ~450k. I used Stefan's law equation to show that’s the radius of the star was less than the radius of the sun.

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#10

I too did that, I also worked out the distance it needed to be at to have a temeprature of 290K, which was 3.something*10^9

(Original post by

for the luminosity 6 marker I worked out the average temp for both planets, and the planet which was 9 x 10^x m away was habitable for life because it had a temp of ~190k. I concluded that the closer planet wasn’t habitable for life because it’s temp was ~450k. I used Stefan's law equation to show that’s the radius of the star was less than the radius of the sun.

**badmotorfinger**)for the luminosity 6 marker I worked out the average temp for both planets, and the planet which was 9 x 10^x m away was habitable for life because it had a temp of ~190k. I concluded that the closer planet wasn’t habitable for life because it’s temp was ~450k. I used Stefan's law equation to show that’s the radius of the star was less than the radius of the sun.

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#11

**badmotorfinger**)

for the luminosity 6 marker I worked out the average temp for both planets, and the planet which was 9 x 10^x m away was habitable for life because it had a temp of ~190k. I concluded that the closer planet wasn’t habitable for life because it’s temp was ~450k. I used Stefan's law equation to show that’s the radius of the star was less than the radius of the sun.

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#12

do you lose marks if you don’t round to a certain amount of sig figs like for the 8500 one I wrote to 4 sig figs

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#14

I remember the parsec question roughly. I got 0.78 parsecs for the star And distance in light years is 4.2

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#15

Did you guys use sine or cos for that amplitude question, since it started at its lowest point (-A) I used cos and that gave me a value of 0.58, I converted to radians as well

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#17

I think you use cos and I forgot radians but a friend of mine told me they got 0.079 so idk

(Original post by

Did you guys use sine or cos for that amplitude question, since it started at its lowest point (-A) I used cos and that gave me a value of 0.58, I converted to radians as well

**muqeet137**)Did you guys use sine or cos for that amplitude question, since it started at its lowest point (-A) I used cos and that gave me a value of 0.58, I converted to radians as well

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#19

I used the equation they gave you in the question, was something like T^4.R/L2 = constant where T = the temperature of the planet orbiting the star so i worked out the constant and applied it to planets orbiting Trappist-1 or whatever it was called

(Original post by

how did you use stefan's law to calculate the temperature of the planets? i thought stefan's law was only about calculating the temperature of stars, not planets

**jason0597**)how did you use stefan's law to calculate the temperature of the planets? i thought stefan's law was only about calculating the temperature of stars, not planets

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#20

I probably put it in my calculator wrong, nothing new for me lol

(Original post by

I think you use cos and I forgot radians but a friend of mine told me they got 0.079 so idk

**B0redBrioche**)I think you use cos and I forgot radians but a friend of mine told me they got 0.079 so idk

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