Measuring the mass and linear dimensions of the block

In summary: C, ±0.05 gcm^-3. in summary, the uncertainty in the calculated density of the rectangular block is ±0.05 gcm^-3.
  • #1
jinx007
62
0
The density of the material of a rectangular block is determined by measuring the mass and
linear dimensions of the block. The table shows the results obtained, together with their
uncertainties.

mass = (25.0 ± 0.1)g
length = (5.00 ± 0.01) cm
breadth = (2.00 ± 0.01) cm
height = (1.00 ± 0.01) cm

The density is calculated to be 2.50gcm–3
.

What is the uncertainty in this result?
A ± 0.01gcm–3
B ± 0.02 gcm–3
C ± 0.05 gcm–3
D ± 0.13gcm–3


According to the book the answer is C and i am having D as answer..

my work

(o.01) x 3 = 0.3

0.3 + 0.01 = 0.13

i cannot figure out where is the mistake help
 
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  • #2
you should add up the fractional uncertainties not the absolute uncertainties.
 
  • #3
arkofnoah said:
you should add up the fractional uncertainties not the absolute uncertainties.

aww fractional error...but the question deal with uncertainty..can you start it for be i will get a better idea
 
  • #4
jinx007 said:
aww fractional error...but the question deal with uncertainty..can you start it for be i will get a better idea

?? I don't get you.
 
  • #5
arkofnoah said:
?? I don't get you.

the question is about uncertainty..why are you working with fractional error...please start the number...work out the first part i will get a better idea of how to attempt the question
 
  • #6
jinx007 said:
the question is about uncertainty..why are you working with fractional error...please start the number...work out the first part i will get a better idea of how to attempt the question

isn't fractional uncertainty (or fractional error if you choose to go by that name) a form of uncertainty? i don't get what's the issue here :confused: and what do you mean by the "first part"?

but anyway the full solution is just this:

total fractional uncertainty: 0.1/25 + 0.01/5 + 0.01/2 + 0.01/1 = 0.021
total absolute uncertainty: 0.021 x 25/(5 x 2 x 1) = 0.0525 = 0.05 gcm^-3
 
Last edited:

1. What is the difference between mass and linear dimensions?

Mass refers to the amount of matter present in an object, whereas linear dimensions refer to the physical size or extent of an object in terms of length, width, and height.

2. How do you measure the mass of a block?

The mass of a block can be measured using a scale or balance. The block is placed on the scale and the reading is taken. The unit of measurement for mass is typically grams (g) or kilograms (kg).

3. How do you measure the linear dimensions of a block?

The linear dimensions of a block can be measured using a ruler or measuring tape. The length, width, and height of the block are measured and recorded in units such as centimeters (cm) or meters (m).

4. Why is it important to measure both the mass and linear dimensions of a block?

Measuring both the mass and linear dimensions of a block provides a more complete understanding of its physical properties. This information can be used to calculate the density of the block, which is an important characteristic for many scientific applications.

5. Are there any factors that can affect the accuracy of measuring the mass and linear dimensions of a block?

Yes, there are several factors that can affect the accuracy of these measurements. These include the precision of the measuring instruments used, the skill of the person taking the measurements, and any external factors such as air currents or temperature changes that may influence the results.

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