A brass cube, 10 cm on a side, is raised in temperature
by200C.
The coefficient of volume expansion ofbrass is
57x10-6/C.
By what percentage is anyone of the 10-cm edges increased
inlength?

Respuesta :

Answer:

[tex]\delta L\%=22.5\%[/tex]

Explanation:

Assuming that the thermal expansion of brass cube occurs isotropically (i.e. equal in all the directions).

Given:

  • length of the cube, [tex]l=10\ cm=0.1\ m[/tex]
  • change in temperature of the cube, [tex]\Deta T=200\^{\circ}C[/tex]
  • coefficient of volume expansion, [tex]\beta=57\times 10^{-6}\ ^{\circ}C^{-1}[/tex]

Hence volume of the cube:

[tex]V=10^{-3}\ m^3[/tex]

Now the volume of the cube after expansion:

[tex]\delta V=V.\beta.\Delta T[/tex]

[tex]\delta V=10^{-3}\times 57\times 10^{-6}\times 200[/tex]

[tex]\delta V=1.14\times 10^{-5}\ m^3[/tex]

Therefore,

[tex]\delta L=0.0225\ m[/tex]

Now the percentage change in the edges of the cube:

[tex]\delta L\%=\frac{\delta L}{L} \times 100[/tex]

[tex]\delta L\%=\frac{0.0225}{0.1} \times 100[/tex]

[tex]\delta L\%=22.5\%[/tex]