imagine a circular metal shaft/bearing.why does it expand only outside no matter in wat direction heat flows?

Question

based on principle of thermal expansion

Answer 1

When any object is heated then the vibrations in the molecules increases.so the molecules attains greater energy to overcome the intermolecular forces.so there potential energy is minimum when they are somewhat more separated than the 'before heating' separation.

due to the increase in the intermolecular attractions the metal as a whole increases in the volume.So the metal expand outside.

it expands in a way to accommodate the increase in volume, and this can be done only by expanding outside.

direction of heat flow doesn't have any effect bcos From any direction the heat come to a molecule, it can do only one and the same thing, increasing the energy of molecule.

Answer 2

While the other answers are reasonably correct, presumably you think that since the bearing is heated it should expand into the hole as well as outward. But imagine you are among the molecules on the inside edge of the hole and heat is applied. The molecules vibrate faster and move further apart so the inside surface expands. All other motions in the material will be be referenced to this surface and thus all the other molecules will move out from the base surface. If you feel the other molecules will somehow push in more than the surface molecules can push back, you are violating the implied statement that the item is evenly heated.

Answer 3

sorry it expands throughout the material ( if evenly heated ) the effect is to make it larger in any direction it can move

Answer 4

First answer +
Material moves in the direction of freedom