Thermal/mechanical properties of matter

In summary: A common balance can be inaccurate if displacement of air is not accounted for. This error can be significant, as demonstrated by a calculation involving water and platinum weights. The percentage error would increase based on neglect of the correction.
  • #1
fasterthanjoao
731
1
1)Explain why a correction must be applied for displacement of air in accurate weighing with a common balance.

Calculate the percentage error which would arise through neglect of this correction in weighing water with platinum weights of density 2.15x10^4 in air density 1.22. (units are kg and m)

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I'm not really sure what to do with this question, is the first part involving the non-uniform distribution of air and the resulting varying pressure or something? hmm. I've scanned a textbook i have access to, it's not very well up on thermal stuff and I can't get to library for a few days. beh. As for the second part, hints are welcome :uhh:
 
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  • #2
Are u sure it's "thermal stuff" and not Archimede's buoyant force...?

Judging from the second problem,it would seem that way...

Daniel.
 
  • #3
yeah me too, that's just what the problem sheet was titled. makes it a little more confusing. I still don't get it though.. :|
 
  • #4
You mean "thermal/mechanical properties of matter"...?Neglecting complete vagueness of the phrase,i think the "mechanical" part would account for Archimede's buoyant force...:wink:

How about asking the dude/chick who gave the problem what on Earth was he/she meaning...

Daniel.
 
  • #5
I am itching to give it a shot...

subscripts a, w and p correspond to air, water and platinum resp.
Buoyant force act on both sides of the scale.


[tex] v_w \rho _w - v_w\rho_a = v_p\rho_p - v_p\rho_a [/tex]


[tex] \frac{v_w}{v_p} = \frac{(\rho_p - \rho_a)}{ \rho_w - \rho_a[/tex]

real weight = [tex] \rho_w v_w[/tex]

Apparent weight = [tex] v_w\rho_w - (v_w\rho_a - v_p\rho_a) [/tex]

% diff = [tex] \frac{\rho_a}{ \rho_w}\left( \frac { \rho_p - \rho_w}{\rho_p - \rho_a} \right)[/tex]


Does it sounds right?

edit: I was attempting to write the ratio of [tex] v_w/v_p[/tex] by rearranging the first equation. It shows up OK in my preview page.
But shows error after submitting.
 
Last edited:

What are the thermal/mechanical properties of matter?

The thermal/mechanical properties of matter refer to the characteristics of a substance that determine how it responds to changes in temperature, pressure, and mechanical forces.

How do temperature and pressure affect the properties of matter?

Temperature and pressure can affect the physical state, density, and elasticity of matter. They can also impact how matter conducts heat and electricity, as well as its melting and boiling points.

What is the difference between thermal and mechanical properties?

Thermal properties refer to how a substance responds to changes in temperature, while mechanical properties refer to how it responds to mechanical forces such as stress, strain, and deformation.

How are the thermal/mechanical properties of matter measured?

The thermal/mechanical properties of matter can be measured using various techniques such as thermal analysis, mechanical testing, and spectroscopy. These methods involve subjecting the substance to different temperatures, pressures, and forces and measuring its response.

Why are the thermal/mechanical properties of matter important?

The thermal/mechanical properties of matter are important in various fields such as materials science, engineering, and physics. They help us understand how substances behave under different conditions and can be used to design and develop new materials for specific applications.

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