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Edexcel Physics Paper 4H - Verdict

Wasn't the hardest of papers, no question on flow of electrons & charge etc.

For the centriputal force question, you had to change kg into g right?

Reply 1

arpeggio

I thought it went alright. I didn't change the kg to g though... I got something like 4000N :s-smilie:

What did you get for the second bit? I got 1.99 orbits, but this is probably wrong as well! Oh well. The majority were OK.

Reply 2

Say cheese!

I thought physics went really well :biggrin:

But I don't think you had to convert the kg to grams :confused:

Well I know I didn't change it and a lot of other ppl didn't either. I just went to check my CGP book and they do it in kg as well.... and I said the satellite orbited twice because of how close the number was to 2.

Reply 3

JayG99

Was okay..
I didn't know you had to re-arrange a formula for the orbits question, so i used other calculations to get an answer of 12.48 orbits...that's wrong right?

Reply 4

Frosty3001

For the orbit question I first changed the formula to make T the subject:

t= 2piR
-----
v

Once I found 't' I then divided the answer by 86400 (seconds in a day), getting 0.5 orbits, which is clearly wrong lol, but how is it done? Will i get method marks at least 2/3?

Reply 5

Theorist

ashmufc: You don't change kg into g as kg is actually the standard unit of mass. So, you're answer will have been wrong I'm afraid ( :redface:

) although I'm sure you'll gain marks for working out.

I got 1.98 orbits as well, using the same method that Frosty3001 did, but I've heard that other people have done it differently, saying they used distance = speed x time and that you can't divide time by time. To be honest, I don't know whether they're right, and I'm not too fussed about it either. I definitely know that the first bit of rearranging the formula, to work out the period is worth three marks.

Yes, apart from that, it seemed OK. And seeing as this only has a 30% weighting to the GCSE, each mark is worth 0.5%, so even dropping 10 marks still gives you 25/30% which isn't bad at all. We'll just have to wait and see...

Best of luck to everyone. :smile:

P.S. A* is normally 85%, right? Does anyone know the grade boundaries for the previous three years - like raw mark instead of UMS, which scales everything out of proportion?

Reply 6

Inflation

Noooo! LOL I converted to grams.

Anway, I got 1.98 and put that squiggly equal sign showing 2.

Reply 7

Frosty3001

Sentooran

ashmufc: You don't change kg into g as kg is actually the standard unit of mass. So, you're answer will have been wrong I'm afraid ( :redface:

P.S. A* is normally 85%, right? Does anyone know the grade boundaries for the previous three years - like raw mark instead of UMS, which scales everything out of proportion?

So Sentooran if i did the same method as you (T/ 84600 seconds), why did i get 0.5 and not 1.98???????????????/

Reply 8

JayG99

I'm an idiot, so go easy on me.
I did the distance of the orbit (m) divided by the speed (m/s), which gives the time it takes to cover one orbit, in seconds, right? I then simply did 86400 divided by the answer i got for how long one orbit takes, and wouldn't that give me how many orbits in a day? 12.48?
Yeah, probabily wrong, but oh well.

Reply 9

arpeggio

I think I did the same thing as you, but I still got 1.99. I worked out the time for one orbit and then divided 86400s (24hr) by this time to get my answer. Are you sure you got the right value for the orbital time? The table had the values for the radius of the earth as well as the radius of the orbit - so maybe one of us used the wrong one in the calculation. I wish there was a way of knowing the mark scheme now...

Reply 10

JayG99

xemmajanex

Yeah, if only.
Well lets just forget about it now till results day! :biggrin:

Thanks for your reply though.

Reply 11

Jason_K

I messed this one up, rather not take about it

Reply 12

Theorist

Frosty3001

So Sentooran if i did the same method as you (T/ 84600 seconds), why did i get 0.5 and not 1.98???????????????/

I'm not sure... I'm definitely sure that it was 1.98 as I checked it several times. Sorry about that. :redface:

However, can we just clarify something: The radius that you were meant to use in your calculations was the one in the table as this was the radius of the orbit, from the centre of the Earth, where the gravitational pull is. In otherwords, the radius used in the calculations should have been 2.7 x 10^7 m. It was not the answer to the first question which asked you to find the height of the orbit above the Earth's surface. This may be where the difference arises.