2011 VCAA Physics Significant Figures Question

[golden]

How accurate should our answers be in Physics?

If we leave values in our calculator to later on use, will they still accept this?

I keep getting different answers to the worked solutions, but essentially it is still correct. The only discrepancy arises due to the significant figures issue, where I am quite reluctant to round off as commonly seen in the solutions.

[jinny1]

i wud like to know to, it's quite equivocal

[costa94]

decimal places matter more than significant figures in physics
theyre not as stingy as chem

[golden]

decimal places matter more than significant figures in physics
theyre not as stingy as chem

Are they strict about the use though?
Eg. The answers say: 303 J and I get 302.9 J would I lose a mark?

Like chemistry, should I use the values as given in the solutions as a guide to how many decimal places / significant figures I should use?

[Lasercookie]

Like chemistry, should I use the values as given in the solutions as a guide to how many decimal places / significant figures I should use?

I reckon that's the best way to go, looking at the significant figures given in the question and basing it off that.
I wouldn't worry about it that much, maybe if you have time left at the end you can check your significant figure usage.

To be honest, when I judge how many significant figures to use, the system I mainly use is what looks nicer. I would be writing 303 J in the box. In my working out I would be writing 302.9 J in my working out, and then showing how I rounded it off as well .

[jinny1]

How wud u 'show' that u have rounded off??

[Lasercookie]

How wud u 'show' that u have rounded off??

I usually just do it in steps like this:




edit: I stuffed up doing basic maths

[jinny1]

If the next question required you to use the answer you got previously, can you use the rounded off answer for the calculations??

[Lasercookie]

If the next question required you to use the answer you got previously, can you use the rounded off answer for the calculations??

I'm not sure if you can, sometimes the trial exam worked solutions do it. However, my teacher emphasised to never use a rounded value in your calcuations.

It's not that much effort to carry over your previous answer on your calculator. Also, answers usually reduce to fractions anyway (obviously you don't write a fraction in the box), so that eliminates the need to round off in your working out anyway.

[golden]

If the next question required you to use the answer you got previously, can you use the rounded off answer for the calculations??

After what Laseredd said I would just leave the value in your calculator possibly by storing in as x or y etc.

[Halil]

Leaving your answer in decimals is always the best I believe. Even if you need it for the following question, you will acquire a more accurate answer. The only time you should round off is if the question asks for it

[xZero]

You can round the answer but if you need to use the previous result use the