Physics Nonsense
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So, today at 5am in the morning, I was making a "Grilled Nutella sandwich". Every time I make said sandwich, the inner outside of the bread is less cooked than the edges. That doesn't seem right.
Isn't it supposed to be the other way around? The outside should heat the middle, therefore giving it endothermic heat, right? Somebody bring a physicist.
Isn't it supposed to be the other way around? The outside should heat the middle, therefore giving it endothermic heat, right? Somebody bring a physicist.
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Disclaimer: I am not a physicist, but...
Heat transfer by contact is more efficient than by radiation. Technically, the heat you feel when you hold your hand over a hot frying pan is being transferred to air molecules which you feel, but for the average person "heat radiating from the frying pan" is a workable understanding. You can hold your hand over a hot pan longer than you can stand to physically touch it, because touching it lets a *lot* more heat transfer to your skin.
The outside crust is more densely packed than the softer inside; compare the porous structure of the inside to the crust. There's more contact with the pan along the crust to transfer heat to, so more heat is absorbed along the crust. However there's fewer connections to the softer inside, so fewer channels for heat to follow. The crust retains more heat than it passes along and gets cooked more thoroughly.
On a materials standpoint, the crust is stiffer than the inside. If you look at a slice of bread it is nearly always thinner in the center than along the crust. The tension in bread tries to shrink it. You can see some of this effect in the warped shapes of dried out slices. The stiffer crust resists this shrinkage, but you still wind up with a lighter contact with the pan away from the crust.
Note that the inside is also more flexible, and tends to sag. This is why the center of a side tends to be more cooked than the area between the center and the crust.
Heat transfer by contact is more efficient than by radiation. Technically, the heat you feel when you hold your hand over a hot frying pan is being transferred to air molecules which you feel, but for the average person "heat radiating from the frying pan" is a workable understanding. You can hold your hand over a hot pan longer than you can stand to physically touch it, because touching it lets a *lot* more heat transfer to your skin.
The outside crust is more densely packed than the softer inside; compare the porous structure of the inside to the crust. There's more contact with the pan along the crust to transfer heat to, so more heat is absorbed along the crust. However there's fewer connections to the softer inside, so fewer channels for heat to follow. The crust retains more heat than it passes along and gets cooked more thoroughly.
On a materials standpoint, the crust is stiffer than the inside. If you look at a slice of bread it is nearly always thinner in the center than along the crust. The tension in bread tries to shrink it. You can see some of this effect in the warped shapes of dried out slices. The stiffer crust resists this shrinkage, but you still wind up with a lighter contact with the pan away from the crust.
Note that the inside is also more flexible, and tends to sag. This is why the center of a side tends to be more cooked than the area between the center and the crust.