A cuboid ABCDEFGH is anisotropic. Let α₁, α₂ and α₃ be its linear-expansion coefficients along x, y and z, respectively, with α₁=1×10⁻⁵ °C⁻¹, α₂=2×10⁻⁵ °C⁻¹ and α₃=3×10⁻⁵ °C⁻¹. Which superficial-expansion coefficient is possible?
Options

Question

A cuboid ABCDEFGH is anisotropic. Let α₁, α₂ and α₃ be its linear-expansion coefficients along x, y and z, respectively, with α₁=1×10⁻⁵ °C⁻¹, α₂=2×10⁻⁵ °C⁻¹ and α₃=3×10⁻⁵ °C⁻¹. Which superficial-expansion coefficient is possible?

Options

G1 Physics · Accepted Answer

For a rectangular face, the superficial-expansion coefficient is the sum of the two linear coefficients lying in that face. For face CDEH the relevant coefficients add to 3×10⁻⁵ °C⁻¹, so option C is correct.