Isaac Physics help

Original post by yusyus

you obtain the following results for the time period of a pendulum: (561,563,569,562,565)ns. None of these results are anomalous. You are then told that the accepted value is 560.5ns. Does this lie within your error bars?

I got the average of 564 and the uncertainty of +/- 4
I put yes but it said incorrect
what have I done wrong?

hm i'm actually not too sure on this one. So I did half the range 0.5*(569 - 561) = 4 to get the absolute uncertainty, and I think you've done the same. So the range should be 560 - 568. I'd have put Yes as well tbh. maybe isaac physics is wrong on this one ? Your method seems pretty sound. sorry i couldn't be much help.

Reply 2

OP

Original post by levi ackerman

hm i'm actually not too sure on this one. So I did half the range 0.5*(569 - 561) = 4 to get the absolute uncertainty, and I think you've done the same. So the range should be 560 - 568. I'd have put Yes as well tbh. maybe isaac physics is wrong on this one ? Your method seems pretty sound. sorry i couldn't be much help.

no problem, I hate uncertainty tbh are you a uni student btw? or doing A level?

Reply 3

Original post by yusyus

no problem, I hate uncertainty tbh are you a uni student btw? or doing A level?

Yeah, it's a weird topic. There's not a lot of questions to practice from, which is a pain.

Currently in year 13 :smile:

Reply 4

OP

Original post by levi ackerman

Yeah, it's a weird topic. There's not a lot of questions to practice from, which is a pain.

Currently in year 13 :smile:

ahh same which board are you doing?

Reply 5

Radioactivedecay

16

I don't think they meant uncertainty when they said error bars, error bars have a formula for which you need to calculate the standard deviation if I recall correctly.

Reply 6

OMG354

18

do you know the length of the thread on which the ball is attached to???

Reply 7

Original post by yusyus

ahh same which board are you doing?

AQA. it's not too bad actually

Reply 8

G.Y

16

Original post by yusyus

you obtain the following results for the time period of a pendulum: (561,563,569,562,565)ns. None of these results are anomalous. You are then told that the accepted value is 560.5ns. Does this lie within your error bars?

I got the average of 564 and the uncertainty of +/- 4
I put yes but it said incorrect
what have I done wrong?

You need to draw a graph for error bars as far as I know

Reply 9

OMG354

18

if you know the length of the thread, the best thing to do is to cheat the way out :smile:

use the formula :
2pi square root of length over acceleration due to gravity which is 9.80 ms-2 (in chicago)

Reply 10

OP

Original post by Radioactivedecay

I don't think they meant uncertainty when they said error bars, error bars have a formula for which you need to calculate the standard deviation if I recall correctly.

ahh, ive never done anything like that in physics so I guess its past the scope of my spec.
Im just thinking of it as one error bar though because time period is usually avaraged and plot once per ... values so idk how it wouldn't lie in the error bar (s)?

Reply 11

OP

Original post by OMG354

if you know the length of the thread, the best thing to do is to cheat the way out :smile:

use the formula :
2pi square root of length over acceleration due to gravity which is 9.80 ms-2 (in chicago)

nah all of the given information is there, I think this question is more based on the uncertainty method than anything anyway

Reply 12

OMG354

18

Original post by yusyus

ahh, ive never done anything like that in physics so I guess its past the scope of my spec.
Im just thinking of it as one error bar though because time period is usually avaraged and plot once per ... values so idk how it wouldn't lie in the error bar (s)?

do wat i told you m8

Reply 13

Original post by Radioactivedecay

I don't think they meant uncertainty when they said error bars, error bars have a formula for which you need to calculate the standard deviation if I recall correctly.

ahh that must be it then. I think using absolute uncertainty = error bars worked for a couple of the other Yes/No questions which were similar to this one, so they must've worked by coincidence then.

But it does sound a bit beyond A-level

(edited 6 years ago)

Reply 14

OP

Original post by G.Y

You need to draw a graph for error bars as far as I know

right, but idk what of; all of the information in the question I wrote in the original question. In experiments about time period and a pendulum isn't it that one length is used and then repeats are taken like the ones in the question, then you take the average and the uncertainty and plot graphs from it by changing the length of the string only.

Reply 15

OP

Original post by levi ackerman

AQA. it's not too bad actually

I do AQA too, are you going for an A*?
tbh I don't mind AQA I think Edexcel is easier; the last years experimental paper for AQA i found like impossible and the grade boundaries were super low

Reply 16