# Si units

#1
Just started aqa spec, ive noticed in order to derive si units for quantities i need to know formulas such as f=ma. I havent done physics in 2 years so i have forgotten most of the formulas, i know they are listed in the databook but im sure most people have the main ones memorised which makes things a lot quicker. Does anyone have a list of the ones you memorised for these derivations? Thank u
0
8 months ago
#2
Worth memorizing the whole formula sheet and all associated (where relevant) derivations.
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#3
(Original post by Callicious)
Worth memorizing the whole formula sheet and all associated (where relevant) derivations.
Are there any formulas that arent on the aqa data sheet that we need to know? I could be blind but i dont see the pressure equation on there
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8 months ago
#4
(Original post by Kalon078)
Are there any formulas that arent on the aqa data sheet that we need to know? I could be blind but i dont see the pressure equation on there
I did my AQA stuff back in 2016 (AS) and 2017 (A2) so things might have changed, but most "necessities" in their off-the-shelf form were on that sheet. I never used the sheet, though- you should build up your "mental repertoire" through practice questions. I usually used Sears/Zemansky's Uni Physics w/ Modern Physics in my studies for all my problems, and it gave me a good understanding and also a good mental repertoire of formulae.

Word of advice though- don't become one of the people who rely on the formula sheet and don't know how to "adapt" formulae. The form of the equation and logic behind it is what counts, not the symbols in the equation or whether or not it's on some magic sheet you "have" to refer to.
1
8 months ago
#5
it's probably better to try and understand the formulas too rather than just memorizing

for example F=ma:
this is saying that force which is applied on an object is directly proportional to the acceleration for a given mass. so if you were to graph F=ma then you will get a straight line

also F=GMM/r^2:
The attraction force between too objects is directly proportional to the product of the 2 masses and inversely proportional to the square of the distance between them. graphing F against r you will get a curve with an asymptotes at the axis and the further away the objects are apart, the Force decreases which makes sense

if you understand the formulas then it's less to memorize since you can work out quite quickly how to get there
2
#6
(Original post by Callicious)
I did my AQA stuff back in 2016 (AS) and 2017 (A2) so things might have changed, but most "necessities" in their off-the-shelf form were on that sheet. I never used the sheet, though- you should build up your "mental repertoire" through practice questions. I usually used Sears/Zemansky's Uni Physics w/ Modern Physics in my studies for all my problems, and it gave me a good understanding and also a good mental repertoire of formulae.

Word of advice though- don't become one of the people who rely on the formula sheet and don't know how to "adapt" formulae. The form of the equation and logic behind it is what counts, not the symbols in the equation or whether or not it's on some magic sheet you "have" to refer to.
Gotcha, btw that book you mentioned, you used that during your a level studies or university? Whats it about?
0
#7
(Original post by Joshwoods01)
it's probably better to try and understand the formulas too rather than just memorizing

for example F=ma:
this is saying that force which is applied on an object is directly proportional to the acceleration for a given mass. so if you were to graph F=ma then you will get a straight line

also F=GMM/r^2:
The attraction force between too objects is directly proportional to the product of the 2 masses and inversely proportional to the square of the distance between them. graphing F against r you will get a curve with an asymptotes at the axis and the further away the objects are apart, the Force decreases which makes sense

if you understand the formulas then it's less to memorize since you can work out quite quickly how to get there
I see, its just at the beginning of the course with the whole si unit thing they expect you to know these formulas in order to do them so i just thought id have em memorised. Will definitely try to understand them though as i go through the course.
0
8 months ago
#8
(Original post by Kalon078)
Gotcha, btw that book you mentioned, you used that during your a level studies or university? Whats it about?
Bought it in the 2nd semester of AS, right after Winter. Took me from a U to an A by the end of my AS, to an A* by the end of my A2. It was my bible, and I its divine follower. Just a generic run-of-the-mill physics textbook, nothing special. I used it in 1st year of Uni, too (which is basically just an extension of A2.)

Edit: Emphasis on U. I really was a horrific student at the start of my A-Levels and it's a miracle I made it that far- my GCSE's were pretty awful too!
Last edited by Callicious; 8 months ago
0
#9
(Original post by Callicious)
Bought it in the 2nd semester of AS, right after Winter. Took me from a U to an A by the end of my AS, to an A* by the end of my A2. It was my bible, and I its divine follower. Just a generic run-of-the-mill physics textbook, nothing special. I used it in 1st year of Uni, too (which is basically just an extension of A2.)

Edit: Emphasis on U. I really was a horrific student at the start of my A-Levels and it's a miracle I made it that far- my GCSE's were pretty awful too!
Thats pretty amazing, definitely will look into that book.
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