WJEC A2 Physics Unit 4: Fields and Options 8th June 2018

OP

I thought the whole of question 2 was tricky. For the electrostatic force and gravitational force did you check that Fr^2 was the same for both?

Reply 25

UnicornZTV

Original post by Graphitenexus

I used just area by accident instead of volume rip me that’s irritating

I did the same as well hahaha

Reply 26

Welshstig

16

Original post by cowseatmilk

I thought the whole of question 2 was tricky. For the electrostatic force and gravitational force did you check that Fr^2 was the same for both?

Yeah, did you get around 1.5*10^-10 and 1.21*10^10?

Reply 27

Original post by Welshstig

I saw it in a past paper, I still don't quite understand it. Basically Vrot and Vrecessional add to make Vradial, the velocity towards you or away iirc, not too sure tbh. I think I got that a bit wrong

I’ve seen something similar in a past paper. I worked out the velocities for the two shifts, found the mean of those as one of the two answers and then did the difference between the mean and either of them as the second answer but I didn’t know which was which or if that’s even right at all - that’s just all I remembered from that past paper

Reply 28

AverageJoe77

Original post by cowseatmilk

I thought the whole of question 2 was tricky. For the electrostatic force and gravitational force did you check that Fr^2 was the same for both?

I’m hoping they’d accept a few methods for that because I just worked them out and said subtracting would be = 0.

Reply 29

OP

Original post by Welshstig

Yeah, did you get around 1.5*10^-10 and 1.21*10^10?

Yes I did! I thought I messed that one up.

Reply 30

Original post by Welshstig

Yeah, did you get around 1.5*10^-10 and 1.21*10^10?

Did you get that gravitational force was larger than the electrostatic force for the question asking if the charge would be large enough for something or other?

(edited 5 years ago)

Reply 31

Welshstig

16

Original post by Graphitenexus

Did you get that gravitational force was larger than the electrostatic force for the question asking if the charge would be large enough for something or other?

Pretty much

Reply 32

AverageJoe77

Original post by Welshstig

I saw it in a past paper, I still don't quite understand it. Basically Vrot and Vrecessional add to make Vradial, the velocity towards you or away iirc, not too sure tbh. I think I got that a bit wrong

Found that bit really hard. I worked out v for both, and said blue shift = recessional velocity - rotational, and red shift = Recessional + rotational. I worked out the difference and divided by two for rotational and then just substituted that in for Recessional. Don’t know if working out the difference was the right thing to do.

Reply 33

Original post by Welshstig

Pretty much

And for the last part of the first question what did you get as the resistance?

Reply 34

OP

Did anyone else get a ridiculously small percentage like times 10^-38??

Reply 35

Original post by cowseatmilk

Did anyone else get a ridiculously small percentage like times 10^-38??

Yeah I did, for that electron question. I think mines a bit off though as I used nucleon number of 2 rather than 1

Reply 36

OP

Original post by Graphitenexus

Yeah I did, for that electron question. I think mines a bit off though as I used nucleon number of 2 rather than 1

Dw I did the same. We should get method marks though

Reply 37

AverageJoe77

Original post by cowseatmilk

Did anyone else get a ridiculously small percentage like times 10^-38??

Yeah I think so, I worked out number of electrons lost/(mass of sun/mass of hydrogen atom x Mass of an electron)

Reply 38

Welshstig

16

Original post by Graphitenexus

And for the last part of the first question what did you get as the resistance?

4444.44 ohms

Reply 39