SM Exam 2 2009 Suggested Solutions.

[/0]

lol did you round up? I rounded up got 1297    x_x

[arthurk]

i had lots of time at the end to do that question so i was just like lololololol
saying fuck every 10 seconds.
I ended up rounding down, it was 50/50 shot im glad god was on my side^^
no one else in my class answered it
One person got -3 for time and was just like fuck this

[TrueTears]

My cas wouldnt let me do the last question and tried to give me negative time as the only answer so i had to trial and error til i got 1200
Took me twenty minutes but i got it to 3 decimal places
then final answer was like 1296.49 i was like oh shiz gg nearest metre i trialled and errored so which way do i round

Yeah last question was gay I knew my calc was fucking up because I sketched it and I knew t had to be between and ~500 ish so when the CAS gave t = -3... or some shit I knew it was wrong.

[arthurk]

yeah i graphed it as well tried integrating on the graph as well but that took a while
How did you end up doing it?

[TrueTears]

yeah i graphed it as well tried integrating on the graph as well but that took a while
How did you end up doing it?

The way I did in solutions

[jimmy999]

what i did was took the fact that at t = 180, the depth is at 880m, and that the velocity is pretty much constant at 4.9m/s.





Distance travelled by the boat

Then after using pythagoras you get distance = 1296m

[NE2000]

^^ smart.

Yeah I did extended response first and I wanted to get into MC so I put it in the calc quickly and waited. And kept waiting. And out comes -3. I manually found the antiderivative and put it into the graph and made the window huge and just hoped for the intersection. Large windows (it wasn't 10000 type large, I could still see the shape of the graph) doesn't reduce accuracy does it?

edit: checked, no it doesn't reduce accuracy

[arthurk]

So you assumed that the tiny increases in velocity were negligible as it was closer to the limiting velocity
interesting, how did ur working play out though. Is that sort of reasoning acceptable?

and TT im too scared to look at ur solutions lol

[NE2000]

Yeah jimmy's working's fine imo. It's a fair assumption given our knowledge of the terminal velocity

[arthurk]

VCAA must have known it was impossible for us to integrate it properly with ti89
such pros

[TrueTears]

Ah ok this is what I did:

[arthurk]

Would have sucked though if the slight inaccuracy lead to a shift of 1 metre from the answer

[arthurk]

oh i was just thinking about placing a domain if it would have worked
i guess it did
should have thought of it during the exam

[TrueTears]

oh i was just thinking about placing a domain if it would have worked
i guess it did
should have thought of it during the exam

Yeah placing the domain was the trick

Basically after sketching I approximated the domain, pretty primitive way, but nonetheless leads to the right answer.

[arthurk]

I see u used x to refer to 2 different numbers in ur answer