In choosing a correct physics equation , one thing to check is its homogeneity . But if two equations are homogenous , the books tell us that we should conduct experiments and plot the graph for both equations . However , after getting our results , which graph is the correct one ? One book tells me that the one with a straight line from origin is correct , another one chooses a straight line not from zero over another graph which is a curve .

Which is which ?

I know , but in some of the practices they give a few equations and it asks to choose the correct one . Graphs must be drawn , and then the correct equation is selected based on the graph . My question is , what criteria are we looking for when looking at the graphs drawn ? Whether it is linear or not ? Whether it starts from zero or not ?

Are you referring to the old Malay version textbook your teacher gave you ?

So Oxford Fajar takes Matrices to a whole new level ? Interesting ...

Have you touched a bit on Physics , or/and Chemistry ?

I enjoyed this short article !

One question : How did he come to the conclusion that his body's volume was the same as the volume of water displaced by his body ? Since his body is an irregular-shaped object and cannot be measured .

I see something here . Does it involve factorising using difference between two squares , 3+7+11+15 ... , and -1 ?

This post has been edited by maximR: Dec 24 2013, 01:43 PM

I'm glad I had the idea .

I probably would have to look at your series tutorials to understand crazywing's workings , still not familiar with the summation notation . I understand Shank's .

Critical_Fallacy

I'm sorry I didn't follow many of the things you've taught in your tutorials , I'm so far behind . I feel like I'm not disciplined enough , not working at the pace as my Sensei's . I will try my best to finish all your tutorials and exercises as I'm now waiting for my L license .

One thing that I want to say is that my knowledge on Matrices is still very shallow ( SPM Level ) . I only know how to compute the usual Matrices with usual dimensions as in SPM . I've always paid little attention on Mathematics which has a rigid algorithm , I found them to be quite dry . But looking at the discussions here about so many interesting properties and uses of Matrices , I'm fascinated by it and want to learn more .

I have one question and I hope you can answer it .

Helium is an interesting element because when it's cooled to very low temperatures , it does not freeze into a solid , instead , it becomes liquid helium , a superfluid which flows without viscosity .

Landau , a Russian physicist came up with a complicated equation which described the property of liquid helium which was based on the assumption that the atoms must be very far apart .

However , Feynman decided that there was a simpler and more elegant solution to the problem and came up with his own using simple assumptions and reasoned through to get to an equation like Landau's . My question is , what are Landau's and Feynman's equations , and are the diagrams involved with Feynman's ? Thank you . Leonard Susskind mentioned that a bright high school student would understand Feynman's solution but did not mention the actual name of the equation .

Finally . Thank you ! When Susskind mentioned 'bright' high school student , he did really mean 'bright' because this is still beyond me .

Critical_Fallacy I don't think I can , but I'll leave it to the others to come up with a simplification .

I've been away to study STPM Kinematics and Dynamics . I must say that STPM Physics is on a whole new level compared with SPM Physics . Here's one question which I need help on :

Two objects with masses m1 and m2 have the same kinetic energy . What is the ratio of the momentum of mass m1 to momentum of mass m2 ?

- On a sidenote , I've finally studied Sequences and Series using sigma notation and only now do I comprehend the posts about formulae for the series of squares , cubes , etc . And I saw many cool tricks to come up with a simple formula for a sequence !

I'd like to get First Term and Second Term STPM Maths T books alongside your printed tutorials and start working on them , if I can finish those I think I'd be ready for A Level Maths and a little bit of A Level Further Maths .

This post has been edited by maximR: Dec 31 2013, 06:10 PM

Yes , this took the most time as I had to play with the equations and think about the different cases for the concepts to sink in . For example , the object that is projected at an angle doesn't accelerate in the horizontal direction at all . Another thing which I want to point out ( which is incorrectly stated in SPM ) is about the sign of g in kinematic problems .

Critical_Fallacy and v1n0d

Look at what I found !

http://eprints.usm.my/view/subjects/

They say I'm weird but delicious things like this make me go " " . I actually prefer this ( although I understand 0.1% of it ) to parties and countdowns .

I still haven't found a friend who has the same wavelength as me .

Hopefully at uni , I'll finally be able to talk to someone whose eyes glimmer when reading about stuff like the curving of space-time , even in layman's terms . Nobody is interested in what I'm interested in . Everyone's so career oriented that I want to get out of this shell , this small fishing village to somewhere which hopefully would provide me with academic stimulation which I'd really appreciate .

I've been living for 18 years ( almost ) as a lonely kid , thank Goodness there's this thing called the internet .

This post has been edited by maximR: Jan 1 2014, 06:08 PM

Oh . But it'd be better if you do what you love .

Well , I've officially retired from high school so I don't have a Physics teacher . It's all up to me , the books , and the internet .

I have seen the term escape velocity before in my book but it's not under projectile motion , it's under gravitation . The derivation is different , it involves kinetic energy and Newton's law of universal gravitation . I understand that derivation . Is there another derivation using that range formula ?

College lectures have this fundamental kinematics equation :

x = x0 + v0t + 1/2 at^2

But my textbooks say this , and the derivation seems correct :

x = v0t + 1/2 at^2

Is the term x0 really necessary , Critical_Fallacy ?

I didn't want to answer this question because I've seen this question and it has been demonstrated experimentally in this lecture , hence , it's a little bit unfair .



And thanks for your explanation on the change in displacement in kinematics equations . All textbooks , be it SPM or STPM do not mention this important fact , because the initial displacement is always assumed to be zero . The important thing to realise is the freedom in choosing increasing values of x and the coordinate system , with this , students will never be confused and make mistakes about the sign of g in different situations .

I have another question : In order to increase the angle of landing ( projectile motion ) when a bullet is fired horizontally , do we increase the height from which the bullet is fired ( or vice-versa ) and increase the initial velocity of the bullet ( or vice-versa ) ? I've tried proving this using the equations , and I came to the conclusion that height should be increased and velocity should also be increased . I need clarification . Thanks .

Critical_Fallacy

Sometimes all you need is the push in the right direction . Sometimes something so obvious eludes you . So forgive me if this is very simple , but I'd dearly want to know , why is i' taken to be equal to i cos phi + j sin phi ? This is about rotation of Cartesian Coordinate System .




Shouldn't the projection of i' on the horizontal axis be i' cos phi ? How to show that :

i' = i cos phi + j sin phi ?

This post has been edited by maximR: Jan 3 2014, 11:11 PM