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i disagree. we define *proper length* to be the length measured in the frame of reference where the thing you're measuring is stationary, so the proper length in this case would be inside the train. hence, in all other frames of reference, the length is shorter...

question to number one... if u want to be really pedantic you could chuck in hydronium and hydrogen ions.

the displacement is 50. therefore, 50 = (1/2)(9.8)t^2 work out t. then use range = Ux * t.

1/c is the time it takes light to move 1m. since distance/velocity = time. distance = 1m velocity = c time: 1/c

i need some clarification please. this is somewhat contradictory. so we have the train moving at 0.8c and theres an observer outside. inside the train, a passenger observes a light wave moving 1metre in 1/c seconds. outside, the distance observed is shorter. i.e. the light moves...

ssglain:

did you mean f(x), where f(x)>0 for all values of x for which the curve runs along the asymptote? i mean, you can't even take the sqrt of f(x)<0.

it takes the cars 1500/(5+10) seconds to meet. in that time, the plane hasnt stopped moving. therefore, the plane has travelled 20 * 1500/(5+10) meters. 20*1500/15 = 20*100 = 2000m = 2 km.

tips for those doing the asx game: there are basically two ways to win: 1. share values generally rises in the duration of the game - always have 100% of your money in shares. if you want to win (since losing whatever amount of money doesn't matter), you need to have maximum profits. 2. if...

which is scary when you think about it - some people in my school got 0/20 or 2/20 for that last chem assignment.

the dot means multiplication, not decimal.

isn't it a bit early to ask this stuff? like the whole methods of counting thing - i think most schools won't have touched on this yet. and why is this in ext2? isn't this .. 3unit? and you copied this straight from a hsc paper lol (i dont remember how many units it was though)

for hsc maths, f'(x) = 0 : this means either turning point, or horizontal inflexion point f''(x) = 0 : this means inflexion (horizontal or oblique) but as ssglain pointed out, in real life f''(x) = 0 has many cases where it is actually a turning point. (i think it might be because its a...

any recommendations?

I have a query - is the Phoenix book simply questions from past hsc papers classified into different topics? or does it have explanation and additional problems as well? thanks.

w00t Fort Street for the win: completed ext2 topics: Complex Numbers to be completed: Curve Sketching, Conics, Polynomials, Mechanics, Volumes, Integration, Harder 3u topics. way to go.

gosh that's a lot for 1.5 terms! which school is this?

school learnt: complex numbers. (haven't had one class of 4u this year yet) tutor learnt: conics, all of integration except reduction formula self-learnt: polynomials, curve sketching to do: volumes, mechanics, harder 3u.

here's the approach without calculus. (ssglain, i'm disappointed) For f(x) = a*(x + b)^2 - 8 to have a tangent y = 2x at (4,8) two conditions have to be met: 1. f(4) = 8 [the parabola passes through (4,8)] 2. when you solve f(x) with y = 2x, delta = 0. this will leave you with a simultaneous...

the eccentricity of a circle is 0, not 1. (eccentricity of 1 = parabola)