Class of 2025 (2025 HSC CHAT) (1 Viewer)

Aeonium

Member
how is this different from tip to tail?
oh the way i was taught tip to tail was you had to use cosine rule n allat
this gets you the same result it's just 'safer' in my opinion
you still tip to tail the result at the end but if you have like 5 vectors tip to tailed them normally it would be extremely painful

Average Boreduser

Rising Renewal
Like yk v-u and then the u is minus so it gets flipped around but then my friend keeps telling me it's wrong and then I don't get like which way the resultant vector arrowhead is supposed to go
my best advice is for you to not over think vectors- I had the same problem but once I learnt vectors from 3u this crap become comprehendible. note u dont have to know much 3u prelim content to learn it so like nothing is stopping u and u get basically the best from both worlds. + if ur scared to use vecs just use vector component addition. safest option by far as aneoniudfhskdfhsklah said be4

Aeonium

Member
how is this different from tip to tail?
here is a screenshot from my #amazing (corrected) notes

Aeonium

Member
Like yk v-u and then the u is minus so it gets flipped around but then my friend keeps telling me it's wrong and then I don't get like which way the resultant vector arrowhead is supposed to go
a negative vector implies it's just flipped 180 degrees (or the other way if you're doing 3d)
so just flip the vector around then add it

banigul@30

Active Member
incoming yap fest:

okay so here's what i do personally (easier than tip to tail + cosine and more relevant to module 5)
so you can consider each vector kind of like a right angle triangle. you have TWO perpendicular components (cause phys only does 2d vectors)
so you want to break down each vector into $\bg_white x$ and $\bg_white y$ components using trigonometry.

for instance, a vector angled at 30 degrees above the horizon with a magnitude of, say, 45 can be broken down into the component parallel to the horizon and the component perpendicular to the horizon
. View attachment 42620

for this, the perpendicular component is given by $\bg_white 45\sin 30\degree$ while the parallel component is given by $\bg_white 45\cos 30\degree$. with this, you can sum all the perpendicular components and parallel components separately and use pythagoreas to get the resultant (make sure to inverse tan the components to get the final vector)

example:
vector a has a magnitude of 75 and is pointing at N30E, vector B has a magnitude of 30 and is pointing at S45W.
View attachment 42621
you can sum the horizontal components as such:
$\bg_white x=75\cos 60\degree -30\cos 45\degree$
and then vertical:
$\bg_white y=75\sin 60\degree - 30\sin 45\degree$
and then to get the resultant vector, you use pythagoreas $\bg_white \vec{v}=\sqrt{x^2+y^2}$ and inverse tangent for direction

i suggest this method for two reasons
1. it's easier when you have many different vectors (collisions in module 2)
2. you will decompose vectors anyways in module 5 for projectile motion
ALSO I LOWKEY FORGOT BEARINGS BUT LIKE I HOPE THIS MADE SENSE you can also make a table of the x and y components.
EDIT: PLEASE DO NOT FORGET YOUR AXIS LABELS LIKE I DID HERE I'M TOO CEEBS TO DO ANYTHING
ohhhh i get what you mean now, yeah definitely never connect more than 2 vectors at a time, it gets wayy too complicated esp trying to make all the vectors keep their angle, always break it up and then resolve it, i was just confused cause this what we were taught as 'tip to tail' so i didn't know how it was different

Aeonium

Member
ohhhh i get what you mean now, yeah definitely never connect more than 2 vectors at a time, it gets wayy too complicated esp trying to make all the vectors keep their angle, always break it up and then resolve it, i was just confused cause this what we were taught as 'tip to tail' so i didn't know how it was different
yeah components can never get the wrong answer if you define your directions properly and yet my friend & i lost a mark in the first prelim phys assessment because the teacher got a different answer somehow? and when asked, he couldn't even explain why

banigul@30

Active Member
yeah components can never get the wrong answer if you define your directions properly and yet my friend & i lost a mark in the first prelim phys assessment because the teacher got a different answer somehow? and when asked, he couldn't even explain why
lol yeah, my phys tutor didn't tell us about the negative and postive direction thing until like 2-3 lessons in and told us a formula (like next to the horizontal and the resultant) for where to add the angle instead of just measuring it from on a position on the cartesian plane, so we were all sooooo lost and id always get the wrong answer, i think the more self study you do the better you get at actually understanding how to do it properly

did you get the mark in the end?

Last edited:

Aeonium

Member
lol yeah, my phys tutor didn't tell us about the negative and postive direction thing until like 2-3 lessons in and told us a formula (like next to the horizontal and the resultant) for where to add the angle instead of just measuring it from on a position in the cartesian plane, so we were all sooooo lost and id always get the wrong answer, i think the more self study you do the better you get at actually understanding how to do it properly

did you get the mark in the end?
naw components was really straightforward personally it seems like your tutor tried to teach you a shortcut before teaching the content fully; if you understand how negative vectors work then it'd make more sense and if you consider the 3u components form it's also nice

no, neither of us did

banigul@30

Active Member
naw components was really straightforward personally it seems like your tutor tried to teach you a shortcut before teaching the content fully; if you understand how negative vectors work then it'd make more sense and if you consider the 3u components form it's also nice

no, neither of us did
by 3u, do you mean like 3u maths?

notsmartenough

Member
how do i drop out

eternallyboreduser

Well-Known Member
incoming yap fest:

okay so here's what i do personally (easier than tip to tail + cosine and more relevant to module 5)
so you can consider each vector kind of like a right angle triangle. you have TWO perpendicular components (cause phys only does 2d vectors)
so you want to break down each vector into $\bg_white x$ and $\bg_white y$ components using trigonometry.

for instance, a vector angled at 30 degrees above the horizon with a magnitude of, say, 45 can be broken down into the component parallel to the horizon and the component perpendicular to the horizon
. View attachment 42620

for this, the perpendicular component is given by $\bg_white 45\sin 30\degree$ while the parallel component is given by $\bg_white 45\cos 30\degree$. with this, you can sum all the perpendicular components and parallel components separately and use pythagoreas to get the resultant (make sure to inverse tan the components to get the final vector)

example:
vector a has a magnitude of 75 and is pointing at N30E, vector B has a magnitude of 30 and is pointing at S45W.
View attachment 42621
you can sum the horizontal components as such:
$\bg_white x=75\cos 60\degree -30\cos 45\degree$
and then vertical:
$\bg_white y=75\sin 60\degree - 30\sin 45\degree$
and then to get the resultant vector, you use pythagoreas $\bg_white \vec{v}=\sqrt{x^2+y^2}$ and inverse tangent for direction

i suggest this method for two reasons
1. it's easier when you have many different vectors (collisions in module 2)
2. you will decompose vectors anyways in module 5 for projectile motion
ALSO I LOWKEY FORGOT BEARINGS BUT LIKE I HOPE THIS MADE SENSE you can also make a table of the x and y components.
EDIT: PLEASE DO NOT FORGET YOUR AXIS LABELS LIKE I DID HERE I'M TOO CEEBS TO DO ANYTHING
For me thats easy but like the harder qs with relative velocity i just cant get. Like when it comes to math and chem for the harder qs i just have intuition which allows me to lnow what to do but when it comes to physics its like all my intuition disappears and i have no clue whag to do

Aeonium

Member
For me thats easy but like the harder qs with relative velocity i just cant get. Like when it comes to math and chem for the harder qs i just have intuition which allows me to lnow what to do but when it comes to physics its like all my intuition disappears and i have no clue whag to do
hmmm do you have an example of one? is it like a qn where you're given "the velocity of a relative to b is ... and the velocity of a with respect to the ground is ... –> find velocity of b" ?

Sylfiphy

Member
I know this is the easiest thing ever but since we're talking abt physics someone pls tell me how interpret the difference between displacement time graphs, velocity time graphs and acceleration time graphs coz it makes sense until I'm not reading the theory and doing the questions by myself

kkk579

hello
I know this is the easiest thing ever but since we're talking abt physics someone pls tell me how interpret the difference between displacement time graphs, velocity time graphs and acceleration time graphs coz it makes sense until I'm not reading the theory and doing the questions by myself
Wdym by interpret the difference? You should be able to tell just by looking at the lables of fhe axis

Aeonium

Member
I know this is the easiest thing ever but since we're talking abt physics someone pls tell me how interpret the difference between displacement time graphs, velocity time graphs and acceleration time graphs coz it makes sense until I'm not reading the theory and doing the questions by myself
the relationship within each is like
area under velo time graph = displacement
area under accel time graph is velocity