## 4B.9

ayushibanerjee06
Posts: 177
Joined: Thu Jul 11, 2019 12:16 am
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### 4B.9

The question says: In an adiabatic process, no energy is transferred as heat. Indicate whether each of the following statements about an adia- batic process in a closed system is always true, always false, or true in certain conditions (specify the conditions): (a) deltaU= 0; (b) q=0; (c) q < 0; (d) deltaU=q; (e) deltaU = w.
I don't get why d is only true if w=0, I thought it was always true since q will always equal zero if there is no energy transferred as heat.

Ipsita Srinivas 1K
Posts: 50
Joined: Mon Jun 17, 2019 7:24 am

### Re: 4B.9

Yeah, but even if q is zero for an adiabatic process, delta U will still be = q + w. If you want an equation which states that delta U = (only) q, it is irrelevant what the q value actually is; the w value has to be zero for the statement to be true. Here, because we know it is an adiabatic process, in the case of delta U = q, we know delta U = 0.

805312064
Posts: 50
Joined: Thu Jul 11, 2019 12:16 am

### Re: 4B.9

Since q = 0, the only way for deltaU to also be 0 is if w is 0 :)

EvanWang
Posts: 101
Joined: Sat Sep 07, 2019 12:16 am

### Re: 4B.9

When q=0 and deltaU=q+w, then
deltaU=(0)+w
deltaU=w

d states deltaU=q or deltaU=0. For this to be true according to the derivation from before, w must equal 0.