Physics Practicals! (1 Viewer)

[deyveed]

Has anyone done a practical as an hsc assessment?

If you have, what was it and what questions did they ask?

 

[ND]

I did two. One was determining the refractive index of perspex, the other was obtaining a value for g with the use of a pendulum.

 

[deyveed]

Refractive index of perspex?
Which dot point is that under?
I only remember doing that sort of stuff in the Preliminary course

 

[ND]

No idea... Some of the assessments i've had for phys and chem weren't at all related to the syllabus.

 

[ezzy85]

ive done the pendulum thing and on thursday im doing one about cathode rays and balmer series. i dont see how the cathode ray prac will work, condsidering we dont have equipment for 30 people and its got radiation.

 

[stag_j]

back near the start of the year we had one. we werent told what it would be beforehand, so we couldnt really study for it. determine g by letting water drops fall from a separating funnel (think thats what its called - it drips water at an adjustable rate). we had to adjust it so that as one drop hit the surface of the desk, the next one was released. using the v=u+at etc formulas we found g.
i cheated a bit tho - i realised straight away that due to the distance only being ~60cm, it would be extremely difficult to get a reasonable answer, so i used a value of 8.5 for g and worked backwards, allowing for experimental error.
i wouldnt say this was ideal, but it was a hell of a lot easier and faster than standing there for 20min trying to set up the equipment and measure everything with a stopwatch.
(btw, we were only marked on the associated written part of the prac which involved calculations on the results- teachers didnt actually watch our process)

 

[deyveed]

Did they ask you on the importance of any part of the experiment such as "How does the time taken for a drop to fall give us an approximation of g?" or "What are the errors associated with this experiment and how can you overcome these errors?"

 

[ezzy85]

they ask for the reliability and validity of the experiement. so that would include errors and how they can be fixed.

 

[Dash]

They also ask for the variables that need to be kept constant in order for the experiment to be effective in attaining its results...
Its a common questions that pops up now and then...

 

[-X-]

shit...I still dont know what dependent, independant variables are??? lol

Someone care to explain? What else do we need to take care of while doing experiments (ie know ure dep/indepedant variables, etc...)?

hehe thanks

 

[stag_j]

Yes. we had to write down our procedure. and at the end we had to discuss how a more accurate measurement could be made. however as long as you understand the procedure and how the experiment works, and if you're only being assessed on the written component of the task, then i consider my way to be better. this is simply because it greatly reduced the time taken, thus allowing you to spend more time giving detailed answers rather than perfroming an experiemnt to produce results that probably wouldnt produce an even close to accurate value of g.

 

[deyveed]

For the "errors" part, do you just write about how people's reaction times are slow and we cant click that stopwatch fast enough? And just the typical whing on how your experiment can't be as accurate as scientists because of the lab conditions e.g lighting, materials and cracks in the tables?

 

[stag_j]

yep. thats about it.
also, in last years HSC paper, there was a question talking about the errors. two people performed an experiment and got results. one person graphed and drew a line of best fit. the other the other just found the average of the results.
You had to compare their methods and identify the better of the two.
...that's just something to consider

 

[Dash]

Post up sum experiments... we can discuss the variables in them...

That would help sum ppl here...