# I Melting time vs Temperature and Mass

#### h1a8

I recently saw the movie “Man of Steel”. In Superman’s fight with Zod, Superman cuts (by melting) a steel I-beam, that Zod is about to hit him with, with a swipe of his heat vision. To melt steel that fast (under 3 seconds) requires a large temperature. My question is how can we calculate the temperature needed to melt (or heat to a certain temperature) steel of a certain mass within a certain amount or time? Basically a temperature vs time and mass function is what I’m trying to achieve.

Thanks!

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#### mfb

Mentor
There is no such thing. If the steel gets hot enough it will melt without delay (well, maybe picoseconds). How to make a steel bar hot enough throughout the bar is a different question.

#### h1a8

There is no such thing. If the steel gets hot enough it will melt without delay (well, maybe picoseconds). How to make a steel bar hot enough throughout the bar is a different question.
So a 3000 degree arc from a wielding torch could melt a certain amount of steel the same speed as a 2500 degrees arc could?

According to Newtons Law of Heating, it’s takes a certain amount of time for a medium to heat an object to a certain temperature.

#### mfb

Mentor
it’s takes a certain amount of time for a medium to heat an object to a certain temperature
That is a different question than in your original post.
If you consider heat flow from some external heating source to the metal you'll have to consider thermal conductivity, and in general you will need numerical simulations because there is no analytic solution.

#### h1a8

That is a different question than in your original post.
If you consider heat flow from some external heating source to the metal you'll have to consider thermal conductivity, and in general you will need numerical simulations because there is no analytic solution.
I seen the equation
Rate of Heat transfer = k(T1 - T2) /d
Where K is the thermal conductivity, T1 is the temperature of the object 1, T2 is the temperature of object 2,and d is the thickness of the object.
I'm basically trying to calculate how long it will take for a substance of certain size and mass to melt under a given ambient temperature.

#### mfb

Mentor
Where K is the thermal conductivity, T1 is the temperature of the object 1, T2 is the temperature of object 2,and d is the thickness of the object.
That works for flat objects where opposing surfaces have the same constant temperature and there is a steady flow of heat. That is not the situation you have, although that formula can be used in simulations for small mass elements and small time steps.
I'm basically trying to calculate how long it will take for a substance of certain size and mass to melt under a given ambient temperature.
This will likely need a numerical simulation.

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