## Heat versus work

$\Delta U=q+w$

Kayla Tchorz-Dis 1F
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Joined: Thu Jul 13, 2017 3:00 am

### Heat versus work

I'm confused on what I need to know, relevently, about the difference between work and heat. I know that heat is the energy associated with the random motion of particles, and work is energy of ordered motion in one direction, but I'm still confused as to what that really means. Thanks in advance!

SPandya1F
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### Re: Heat versus work

Heat and work are similar in that they both describe energy transfer.
I think of work as referring to something more mechanical, like pushing a piston.
I think of heat as referring to the thermal process thats responsible for temperature differences.

Julianna Thrasher 1B
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Joined: Thu Jul 27, 2017 3:00 am

### Re: Heat versus work

Heat is a form of energy that is transferred due to a temperature difference. Heat flows from a high temperature region to a lower temperature region. Temperature measures the flow of heat energy, or the speed of the random moving particles. Work is "the process of achieving motion against an opposing force" (section 8.2). If a system can do a lot of work, then it possesses a lot of energy. This energy of ordered motion is channeled in one direction in order to do work on of by the system.

Niyanta Joshi 1F
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Joined: Thu Jul 13, 2017 3:00 am

### Re: Heat versus work

I found it interesting that although work and heat are interchangeable forms of energy, while work can be fully transferred into heat, the vice versa is not true. This is because if heat is fully transformed into work, it would violate the laws of entropy, i.e, a closed system's entropy cannot decrease.

Marina Georgies 1C
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Joined: Sat Jul 22, 2017 3:00 am

### Re: Heat versus work

From the textbook: "The fundamental molecular difference between work and heat is related to the orderliness with which atoms in the surroundings move. When energy is transferred as work, the system moves molecules in the surroundings in a definite direction... During the transfer of energy as heat, the molecules in the surroundings are moved in random directions" p. 272

Diego Zavala 2I
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### Re: Heat versus work

Work is very similar to heat except that work has a direction (i.e energy is used to push a piston up) whereas heat is the random collision of fast and slow molecules, causing energy to be transferred from the faster moving molecules to the slower ones.

Ashley Garcia 2L
Posts: 33
Joined: Fri Sep 29, 2017 7:05 am

### Re: Heat versus work

Heat and work are both forms of energy. Heat is the energy associated with the random motion of particles, while work is the energy of ordered motion in a specific direction.

First Law: Heat and work contribute to the total energy of the system. ΔU = q + w
Second Law: Work can be transformed into heat, but heat cannot be transformed into work.

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