errors questions for physics

basilmarket.com forums : Chat | 15 posts archived

thread starter telesyn Sep 07 2009 + PM | QUOTE | PERMALINK | REPORT

if i were to find the possible error range for certain values which have multiplication e.g m/s^2 what do i do to find the total error for a value of gravity e.g. error in time is 00.01 and error in length is 0.1,

arch3rman 09/07/09 + PM | QUOTE | PERMALINK | REPORT

dun get you..post the question?

DeMoNiAk 09/07/09 + PM | QUOTE | PERMALINK | REPORT

I don't get it.

telesyn Sep 07 2009 + PM | QUOTE | PERMALINK | REPORT

im writing a lab report my error from length is 0.05*2 for (both ends of the ruler) and my error from measuring time is 0.01 (smallest scale on digital clock) the thing is i have to get an error for my value of gravity. (which is 9.63 atm) yea btw its only systematic errors

PeacePlease 09/07/09 + PM | QUOTE | PERMALINK | REPORT

You're dropping an object, measuring and timing the time it takes to hit the floor? I remember doing this last year; 9.63 is pretty close.

taleko 09/07/09 + PM | QUOTE | PERMALINK | REPORT

depending on where you are and the accuracy of the measurement of both the time of the fall and the distance of the fall you should get answers ranging anywhere from 9.6-9.8 also depends on air pressure, height from sea level, density of the earth directly below you and tectonics iirc.

A4No0b 09/07/09 + PM | QUOTE | PERMALINK | REPORT

That is entirely up to your teacher. Everyone has their own standards and conventions- so asking basil would do absolutely no help.

taleko 09/07/09 + PM | QUOTE | PERMALINK | REPORT

p.s. air resistance of the object falling.

taleko Sep 07 2009 + PM | QUOTE | PERMALINK | REPORT

also where are you pulling 9.63 from? p.s. interstellar objects like the sun and moon also affect our gravity.

PeacePlease 09/07/09 + PM | QUOTE | PERMALINK | REPORT

taleko : also where are you pulling 9.63 from? My take on it is that it's the acceleration of gravity. He got that by dropping an object from a certain height and timing it.

taleko Sep 07 2009 + PM | QUOTE | PERMALINK | REPORT

[url=http://en.wikipedia.org/wiki/Earth%27s_gravity,]http://en.wikipedia.org/wiki/Earth%27s_gravity,[/url] his little experiment is obviously off. close for a school experiment yes, but obviously off. should be roughly 9.8m/s/s

HokKan 09/07/09 + PM | QUOTE | PERMALINK | REPORT

Unless you are dropping an object with a lot of air resistance or dropping something from a very high place, the difference should not be measurable with (I'm assuming) simple equipment. I think it is from error in timing.

taleko 09/07/09 + PM | QUOTE | PERMALINK | REPORT

the timing problem is fixable with a laser timer and the like, its probably more likely coming from the actual drop of the item...

HokKan 09/07/09 + PM | QUOTE | PERMALINK | REPORT

taleko : the timing problem is fixable with a laser timer and the like, its probably more likely coming from the actual drop of the item... What do you mean the actual drop? Like, if they didn't drop it neutral? I guess this is hard to explain. But I mean, letting it go instead of lifting it up slightly or pushing it down slightly as you do so. Is that what you meant?

taleko Sep 07 2009 + PM | QUOTE | PERMALINK | REPORT

its how it is let go, if its done by hand it will lose alot of speed while the hand is opening, its not an instant thing. but yeah even if they didnt drop it neutrally, like they lifted up or whatever, best way to explain it is imagine firing a bow and arrow, now when you release the bowstring you wont release it absolutely instantly, it will be slowed down off your fingers.