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# Quick question about 'zero errors' watch

1. When I measure a mass using an electronic scale, if i ensure that the scale reads 0.00g (for example) before I palce the mass on the scale, will this 'eliminate zero errors'?

I have a A2 physics assesment next week and I'm not sure about how to 'eliminate zero errors' or what a zero error actually is.

Also, if I want to measure extension of a spring using a metre ruler (precision +/- 0.1cm ) by subtracting the original position of the last coil(h0) from the extended length(h) i.e. extension = (h0-h).

Is there any uncertainty in my measurement of h0 due to the precision of a ruler or is the uncertainty in h0 = 0 because I am using it as a 'zero point/ fiduciary'
2. Yeah that should do it. A zero error happens when your scale reads something other than 0.00g with nothing on it.

There will be uncertainty in h0. If you measure h0 wrong, your value of the difference between the two will be off.
3. (Original post by Xdaamno)
Yeah that should do it. A zero error happens when your scale reads something other than 0.00g with nothing on it.

There will be uncertainty in h0. If you measure h0 wrong, your value of the difference between the two will be off.
Thanks for the response.

So it would be correct forme to say ' Ensure scale reads 0.00g before measuring mass to elminate zero errors in measuring mass'

For extension, if the precision of the ruler is 0.1 cm, and ther eis an uncertainty in both h and h0 will the uncertainty in extension be +/- 0.2 cm ?
4. Yep, that all sounds good.

If you're interested: the AQA ISA would certainly allow that to be calculated at +/-0.2cm, and I think the other boards will accept it too - some think that the uncertainity for each measurement should be +/-0.05cm, or that the two errors combine to give less than +/-0.2cm because the errors will sometimes cancel each other out, but you shouldn't worry.
5. Ok thanks

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