well???

[orangez]

OMFG!! I just realised. I copied another version of the diagram onto my cheat sheet, but guess what? I placed the tension and compression forces at the wrong places (tension at top and comp. at bottom) How dumb is that? Lost 2 marks 

[chid]

Don't worry about it. I know it's two marks and it is a harsh penalty for a small oversight, but that's the nature of this exam. 13 questions for 26 marks in detailed study means that most people will lose more marks than they deserve to for small mistakes (and also there is no consequential)

[pinchies]

Well

As for the kinetic energy question...the answer was D i think...the parabola....heres why...

Since mass of the particle remains constant the ony variable affecting kinetic energy is velocity. Now, at the bottom of its cycle... the particle is moving upward with speed. Its speed then reaches a maximum at the halfway point. then it slowly begins to decelerate as it nears the top as the spring provides force opposing the motion. There..that seems about right....If anyone thinks im wrong go right ahead and point it out. << not meaning to sound arrogant or anything just wanting to encourage constructive criticism.

Cheers

well put!!
I think graph C was of the acceleration and D was of the velocity

[Ninox]

As for the kinetic energy question...the answer was D i think...the parabola....heres why...

Since mass of the particle remains constant the ony variable affecting kinetic energy is velocity. Now, at the bottom of its cycle... the particle is moving upward with speed. Its speed then reaches a maximum at the halfway point. then it slowly begins to decelerate as it nears the top as the spring provides force opposing the motion. There..that seems about right....If anyone thinks im wrong go right ahead and point it out. << not meaning to sound arrogant or anything just wanting to encourage constructive criticism.

Cheers

hey I know that guy!
No enwiabe, I'm not trolling.
good to see that ur doing alright

[Captain]

As for the kinetic energy question...the answer was D i think...the parabola....heres why...

Since mass of the particle remains constant the ony variable affecting kinetic energy is velocity. Now, at the bottom of its cycle... the particle is moving upward with speed. Its speed then reaches a maximum at the halfway point. then it slowly begins to decelerate as it nears the top as the spring provides force opposing the motion. There..that seems about right....If anyone thinks im wrong go right ahead and point it out. << not meaning to sound arrogant or anything just wanting to encourage constructive criticism.

Cheers

I agree Energy Kinetic only varies on velocity.

Now, let's ignore energy for a minute.

Let us pretend, this is a projectile, with no horizontal velocity.

It has a launch velocity, which is it's maximum.  Gravity acts upon it, slowing it down.  It reaches a velocity of 0m/s at the top. [We all agree Energy kinetic must be 0 at the top]

Now, taking the spring into concideration.

The way I see it, is the spring energy is converted to kinetic energy.

As the ball goes higher, this kinetic energy goes into potential energy.

The spring doesn't start compressing until 40cm.  The ball only rises up to 55cm, Hence no energy goes into compression. [I've got the diagram infront of me]

[equinox]

^^hmmm hmmm i see your point....will have to get out a slinky spring to test this out.
BRB

[Mao]

i'm only joining in this debate now

it HAS to be D, the mass changes direction, you are not supposing it changes direction at a velocity other than 0 ?!
REAL LIFE DISCONTINUITY

ps, i have the exam in front of me, but i dont have a scanner either

[equinox]

Excellent..so the slinky sping wasnt required. 

[Captain]

I totally looked at this question in the wrong way.

According to Mao's solutions, I'm sitting on 87/90.

[pinchies]

I totally looked at this question in the wrong way.

According to Mao's solutions, I'm sitting on 87/90.

Nice! Hope it comes out that way for end of year... now they know, they'll make it harder I reckon.

[Mao]

I totally looked at this question in the wrong way.

According to Mao's solutions, I'm sitting on 87/90.

Nice! Hope it comes out that way for end of year... now they know, they'll make it harder I reckon.

i dont think they will

it was overall a good paper, no ambiguity, but the difficulty was there. for once a VCAA paper has some quality to it

i just hope they dont change that, especially the ambiguity part. maybe they've learnt a lesson since the 06 paper

[equinox]

yes me too  87/90 i reckon

[Captain]

I totally looked at this question in the wrong way.

According to Mao's solutions, I'm sitting on 87/90.

Nice! Hope it comes out that way for end of year... now they know, they'll make it harder I reckon.

i dont think they will

it was overall a good paper, no ambiguity, but the difficulty was there. for once a VCAA paper has some quality to it

i just hope they dont change that, especially the ambiguity part. maybe they've learnt a lesson since the 06 paper

This years Physics paper was written by someone different, than the 05, 06 and 07 [pretty sure they were written by the same person]

[equinox]

^^ it shows....the other papers were aweful