What is the absolute uncertainty in your estimate of the total mass?

[simond]

Homework Statement

You measure the mass of a physics textbook to be 2.97±0.07 kg, and use this value to estimate the total mass of 800 identical physics textbooks in the bookstore. What is the absolute uncertainty in your estimate of the total mass?


I have been working on this for a while. I am not sure why I cannot get it. What I have tried is:

0.07(2)=0.014 -- since the uncertainty can go up or down .07kg

then, multiplying the 0.014 by the 800 textbooks, to get 11.2kg.

This however apparently is incorrect. What should I do?

 

[Gear300]

For a value x±dx, in which the error is ±dx, your absolute uncertainty is |±dx| = |dx|. So the magnitude of the maximum error you can get for a book is .07kg. So instead of the .14kg you used, it would be .07kg.

If what I said doesn't work, then it is probably because you're using 0.07(2) = 0.014...which is not right, its actually 0.14.

 

[tomcue]

The absolute uncertainty in your estimate of the total mass can be calculated by using the formula:

Absolute uncertainty = (uncertainty in individual measurement) x (number of objects)

In this case, the uncertainty in the individual measurement is 0.07 kg and the number of textbooks is 800. Therefore, the absolute uncertainty in your estimate of the total mass would be 0.07 kg x 800 = 56 kg.

This means that your estimate of the total mass of 800 textbooks could vary by 56 kg due to the uncertainty in your initial measurement. It is important to note that this is just an estimate and the actual total mass could be slightly higher or lower than your calculated value. It is recommended to always include the uncertainty in your calculations to provide a more accurate and reliable estimate.