Absolute Uncertainty - Enough Information?

[aborder]

Homework Statement

If an electronic scale reads 502.4 g, what is the absolute uncertainty in the mass reading.

Homework Equations

Not sure

The Attempt at a Solution

Not a clue, it seems that there isn't enough information given. How am I supposed to figure out the absolute uncertainty if this is all that is given?

 

[flyingpig]

It should have a label on the scale.

 

[aborder]

That's funny because I was thinking the same thing. Unfortunately it is straight out of a textbook so nothing is given other than the question itself. Not sure how to approach this one. Any ideas?

 

[Haborix]

My first thought is to consider significant figures. If you were given a value of 10, would you think it's reasonable to have an uncertainty of +/- 0.1? Probably not, because the output you have is not given to any decimal places. So in this case where we have 502.4g we should ask how exact can we get before we reach the limit of the measurement.

-Eric

 

[aborder]

My first thought is to consider significant figures. If you were given a value of 10, would you think it's reasonable to have an uncertainty of +/- 0.1? Probably not, because the output you have is not given to any decimal places. So in this case where we have 502.4g we should ask how exact can we get before we reach the limit of the measurement.

-Eric

So then are we saying with absolute certainty that the measurement is 502.4g since no other information is given? Therefore, the uncertainty would be +/- 0.0. Obviously if we were given 502.2 - 502.6 we would know the uncertainty to be +/- 0.2.

 

[Phrak]

It's a lousy question and your text should be burned in an effort to the improvement the human condition.

However

It seems we are supposed to assume the measuring electronics deliver 100% accuracy to the display.

If the actual mass were 502.351 g what would the meter read?
If the actual mass were 502.449 g what would the meter read?

 

[PeterO]

Homework Statement

If an electronic scale reads 502.4 g, what is the absolute uncertainty in the mass reading.

Homework Equations

Not sure

The Attempt at a Solution

Not a clue, it seems that there isn't enough information given. How am I supposed to figure out the absolute uncertainty if this is all that is given?

I think all figure are taken as =- 1/2 of the last digit - unless stated as bigger.

So 502.4 =-0.05

 

[aborder]

It's a lousy question and your text should be burned in an effort to the improvement the human condition.

However

It seems we are supposed to assume the measuring electronics deliver 100% accuracy to the display.

If the actual mass were 502.351 g what would the meter read?
If the actual mass were 502.449 g what would the meter read?

I suppose that it would read 502.4 because it rounds to the nearest tenth. I guess we assume that when only the tenths place is given. The thing is, how do I know what to assume when this isn't discussed in the text.

Yah, fire always brings me comfort. Especially when it involves burning something that is persecuting me.

 

[aborder]

I think all figure are taken as =- 1/2 of the last digit - unless stated as bigger.

So 502.4 =-0.05

Wouldn't it also be + 0.05 as well if the meter rounds to the nearest tenth? I guess we really don't know since there isn't any additional information provided.

 

[PeterO]

Wouldn't it also be + 0.05 as well if the meter rounds to the nearest tenth? I guess we really don't know since there isn't any additional information provided.

Look at the keyboard ... I was too brief with the shift key so got = instead of +

 

[Phrak]

I suppose that it would read 502.4 because it rounds to the nearest tenth. I guess we assume that when only the tenths place is given. The thing is, how do I know what to assume when this isn't discussed in the text.

Given that I've correctly read between the lines of your text, what do you get for the absolute error?

 

[aborder]

given that I've correctly read between the lines of your text, what do you get for the absolute error?

502.4 +/- 0.05

 

[aborder]

Look at the keyboard ... I was too brief with the shift key so got = instead of +

Excellent, thank you.

 

[Phrak]

Look at the keyboard ... I was too brief with the shift key so got = instead of +

That's a good trick. How do you typo "+/-" into "="? The fingers must by flying.

 

[PeterO]

That's a good trick. How do you typo "+/-" into "="? The fingers must by flying.

Not quite, the typo was "=-" instead of "+-"