Exam Discussion

[JoshReid]

What did everyone write for the action reaction question with the 2kg mass suspending by the ceiling.

I said that force that attracts the sphere to the Earth is equal and opposite to the force that the object exerts on the Earth. And due to the relative masses, acceleration of the Earth towards the sphere is negligible. But generally, very poorly done. I choked on far too many questions.

[billyjackson768]

I wrote tension and up, but I honestly am not sure at all...

Yeah that's about it. But the reaction to the top mass was the tension up minus the bit of tension that was added for the second mass.

[mikesguns]

I know this should be in another thread, but does anyone know where the find the 2012 SoM application, the one is VCAA website is the 2011 one I think

[max payne]

Action force was the gravitational force by the Earth on the 2kg sphere, hence the reaction force would be the gravitational force by the sphere on the Earth. Remember that action-reaction forces never act on the same body.

wow..I dont think I would ever have thought of that if I had a million years... Well thats what I get for neglecting theory questions during study
Anyway does anyone know generaly when the itute answers would be up?

[StumbleBum]

I don't think the reaction force is the force on the earth because it is connecting to the string so there is no way it could be that...

[yellowsone31]

The log question was a bitch to me, and yeah tension and up sounds right

[billyjackson768]

Over all I was pretty happy with the exam. I think it may of actually been easier then 2011's. But I did do about 5 exams between my 2011 practice exam and today. So that might of made a difference.

The only thing I think I got wrong was question 7 (I think it was) in structures and materials where you had to find the energy due to the strain or w/e on the steel rod/wire. Completely forgot how to do that and I was there counting squares and multiplying by volume, area and everything and just couldn't find an answer. So I think I guessed either C or D which were 900J or 9000J I think. Other than that I was pretty happy with the 4 mark explanation questions such as the diodes and the only other thing I"m not so sure on was the one where you had to draw an arrow at point P indication which direction the mass would go when the string breaks. I dunno why but I just got confused, to used writing CF as an arrow going towards the centre. So I guessed once the string broke it'd go directly away from the centre.

I found I didn't have much time to spare... only just finished with 5 mins to go luckily thanks to some easy S&M questions which involved little work, just logic to complete. How did everyone else find things for time?

[billyjackson768]

I don't think the reaction force is the force on the earth because it is connecting to the string so there is no way it could be that...

Yeah, reaction force of the earth moving towards the ball would only be if the ball were free falling?

[caluuu]

I forgot work done =change in energy....
HOW GOOD AM I!?

[WhoTookMyUsername]

fml
somehow managed to divide by wrong number in power q . lost 1- 2 marks at least fml

[yellowsone31]

Over all I was pretty happy with the exam. I think it may of actually been easier then 2011's. But I did do about 5 exams between my 2011 practice exam and today. So that might of made a difference.

The only thing I think I got wrong was question 7 (I think it was) in structures and materials where you had to find the energy due to the strain or w/e on the steel rod/wire. Completely forgot how to do that and I was there counting squares and multiplying by volume, area and everything and just couldn't find an answer. So I think I guessed either C or D which were 900J or 9000J I think. Other than that I was pretty happy with the 4 mark explanation questions such as the diodes and the only other thing I"m not so sure on was the one where you had to draw an arrow at point P indication which direction the mass would go when the string breaks. I dunno why but I just got confused, to used writing CF as an arrow going towards the centre. So I guessed once the string broke it'd go directly away from the centre.

I found I didn't have much time to spare... only just finished with 5 mins to go luckily thanks to some easy S&M questions which involved little work, just logic to complete. How did everyone else find things for time?

Finished with like a minute to spare lol, it was so long!

[yellowsone31]

I forgot work done =change in energy....
HOW GOOD AM I!?

dw its only one mark

[studynotes]

i was proud to see drawing of the circuit again! how ever too many explaining questions TT whoever thought the first question would be spring related-.- but it was really easy. Did everyone get B as the answer in order for the ball to be stationary?

[JoshReid]

What was the initial tension in T1?

[studynotes]

I added the frictional forces to find T1 i think it was 800N..