Resisted motion / Mechanics (1 Viewer)

[povodude]

I have learnt the basic topics of 4u -complex numbers, volumes, graphing, integration, conics, pollynomials and harder 3u. I payed like no attention to the resisted motion and mechanics topics, and I was wondering if people think should I bother to learn these topics for the HSC.

Also I only got 30% in the in the CSSA trial(scaled to 50%), Do I have a chance at getting of getting a final mark in 4u of 90+?

 

[ezzy85]

resisted motion isnt hard to learn. most of them follow pretty much the same method. make sure you can do the basic type questions so you dont get 0 for a motion q in the hsc.

 

[Affinity]

Try not to think resisted motion as something different from erh 'normal' motion.

it always, write your D.E. then integrate or solve.

 

[ND]

D.E.?

 

[Rahul]

differential equation? what is it..

 

[Affinity]

soryr, differential equation

for example if they give you something like the resistance is proportional to the velocity of a particle which is also subjected to gravity, then you write the D.E.

y'' = -g - ky'

(or a= -g-kv)

where k is a positive constant.

then work from there.

 

[ND]

Yeh, i just didn't know what D.E. stood for.

 

[Affinity]

ofcourse you know it.
that was for povodude

 

[povodude]

thanks for the tips, it seems kinda easy so I might try to do some

 

[stag_j]

yea i might even go as far as to say its the easiest 4u topic. besides maybe curve sketching but i dont even count that as 4u.

just remember to find out what forces are acting (usually gravity and some kind of resistive force, eg mkv or mkv^2.
then its pretty much just a matter of integrating. remember the different forms for acceleration (ie dv/dt, v.dv/dx) and pick the one that has the variable you are looking for.
do a few question and you'll see that they're all the same really.

 

[Affinity]

if I hear one more comment about curve sketching being easy!

 

[povodude]

oh but it IS easy. The only hard ones are trig inverse or some log graphs, look at more examples if you have troubles

 

[turtle_2468]

It's "EASY" in the sense that you can fudge most of the graph, but it's also hard in that sense. Because being able to fudge means that in fact you can't really draw the shape EXACTLY right
ie if you reproduce a proof in mechanics for example, they have to give you full marks. But if they don't like you or your writing or simply the colour of your ink, so to speak, they can say "hey, this doesn't look like the graph I have in my suggested answers, take a mark off..."

 

[Rahul]

with enough work, everything can be within your capabilities.
i'm not saying you have done no work on graphs affinity.
its just that people's brain works differently...