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A Level OCR Physics A Paper 1 2019 Unofficial Markscheme

Beast9066

5

what answers did you guys get??

Reply 1

mestalion25

7

Around 13.5 for the mass of the sign thing. Idk what question that was sry

Reply 2

B0redBrioche

12

MP choice

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.

(edited 4 years ago)

Reply 3

yellowmarker123

7

i wrote 11kg ffssssssssssssss

Reply 4

jason0597

16

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

Reply 5

muqeet137

11

yh and it rms speed of 650 or something

Original post by jason0597

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

Reply 6

Labib98

12

13.something kg for the mass of the wooden thing

Reply 7

jason0597

16

Original post by Labib98

13.something kg for the mass of the wooden thing

13 or 13.5? cause 13.5 rounds to 14

Reply 8

badmotorfinger

8

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.

Reply 9

muqeet137

11

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 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.

Reply 10

jason0597

16

Original post by 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.

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

Reply 11

PhysicsIlove

9

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

Reply 12

msbx

10

Is there a thread for exploring ?

Reply 13

abzalamirbay

3

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

Reply 14

muqeet137

11

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

Reply 15

abzalamirbay

3

Modelling

Original post by msbx

Is there a thread for exploring ?

Reply 16

B0redBrioche

12

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 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

Reply 17

mestalion25

7

I got force constant as 500000 Nm-1

Reply 18

badmotorfinger

8

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 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