Potetial energy change during heating

[sgstudent]

Homework Statement

when heating i learned that only the kinetic energy component of internal energy increases. However, I also learned that potential energy is related to distance between the particles. So when i heat some solid and it expands does it mean the potential energy has changed as well? I don't think that is the reason for the expansion.

Homework Equations

none

The Attempt at a Solution

i understand that it moves faster but i don't think the amplitude of vibration should increase as i don't think the potential energy increases.

Thanks for the help!

 

[grzz]

... when heating i learned that only the kinetic energy component of internal energy increases ...

Maybe you read the above in a context where an ideal gas is assumed. In an ideal gas it is assumed that there are no intermolecular forces and so there is no potential energy.

 

[sgstudent]

Maybe you read the above in a context where an ideal gas is assumed. In an ideal gas it is assumed that there are no intermolecular forces and so there is no potential energy.

But what about solids? When I heat iron it expands but its potential energy should not increase so what's letting it expand?

 

[grzz]

If the iron expands its potential energy increases.

 

[sgstudent]

If the iron expands its potential energy increases.

So even as it heats up the potential energy changes as well? That's possible?

 

[grzz]

If the iron expands, the interatomic distances must have increased. But atoms attract each other. So the potential energy must increase.

 

[sgstudent]

If the iron expands, the interatomic distances must have increased. But atoms attract each other. So the potential energy must increase.

oh so when we calculate Q=mcΔT it is not complete since we have not taken potential energy into account?

 

[grzz]

When the temperature of a solid is increased, both internal KE and internal PE increase and the specific heat capacity c of a solid must take care of both these increases.