I keep getting “Thermal expansion” questions wrong in Thermal Properties of Matter. What's the trap?
treating a hole in a heated metal plate as shrinking.
The usual trap: treating a hole in a heated metal plate as shrinking. How to avoid it: heat the whole drawing: the hole expands as if it were made of the same material. Go back to the definition — Most materials expand when heated because the average separation between particles increases. For an isotropic solid, area and volume expansion coefficients are approximately 2alpha and 3alpha when alpha is small.
Key point
Thermal expansion
Common mistake
treating a hole in a heated metal plate as shrinking.
Memory tip
heat the whole drawing: the hole expands as if it were made of the same material.
Tap to watch or see it right here — the app stays open (it only opens a quick search if nothing embeddable is found).