Understanding Specific Heat Units (hg-C)

AI Thread Summary
The discussion centers around the confusion regarding the specific heat of air being expressed as 1.05 kJ/hg-C. Participants clarify that specific heat is typically represented in kJ/(kg·C) or kJ/(kg·K), indicating a potential typographical error with "hg" likely being a mistake for "kg." It is emphasized that the correct units for specific heat should reflect energy per unit mass per unit temperature. Additionally, the mention of J/C pertains to heat capacity rather than specific heat. Overall, the consensus is that the original unit notation is incorrect and should be revised.
scumbum22
Messages
6
Reaction score
0
Hopefully this is a really simple question to answer. A problem I have uses the following information:

The specific heat of air = 1.05 kJ/hg-C.

Does anyone know what the hg-C stands for? I know specific heat is usually expressed in terms of J/C, so this is confusing me.
 
Science news on Phys.org
The units of specific heat are energy per unit of mass per unit of temperature. Thus it should read kJ/(kg C). I think you misread the unit and ended up with hg instead of kg.
 
Nope, I double checked and the units are definitely kJ/(hg-C). Any ideas as to what the hg may be? Is it some reference to mercury?
 
It doesn't refer to mercury. Let's say it's a typing mistake. I stand by my previous post
 
The specific heat of air is of the order of 1 kJ/kg.K (or kJ/kg.C). The exact value depends on temperature. So it is a typo, no doubt.
The units J/C (asuming C stands for Celsius degree) are for heat capacity and not for specific heat.
 
Been around 40 years since I took basic physics in college and while I remember doing some examples of insulation values / energy conduction, I doubt I could to the math now even if I could find the formulas. I have some some corrugated plastic sheet (think of the plastic signs you see on the side of the road) that is used in bee hives. Also have some used in a green house though a bit different in dimensions than this example but the general approach should still apply. Typically, both...
Problem: You’re an Uber driver with a Tesla Model 3. Today’s low: 30F, high: 65F. You want to reach a USD$ profit target in the least number of hours, but your choices could have added cost. Do you preheat the battery only when you are headed to the charging station (to increase the charging rate by warming the battery — however the battery might not be “warm enough” when your reach the charger and thus slower charging rates), or do you always “navigate to the charger” the entire day (which...
Thread 'Is Callen right in claiming dQ=TdS for all quasi-static processes?'
Hello! I am currently reading the second edition of Callen's Thermodynamics and an Introduction to Thermostatistics, and I have a question regarding Callen's definition of quasi-static. On page 96, Callen says: Another way of characterizing Callen's definition is that a process is quasi-static if it traces out a continuous curve in the system's configuration space. So far it's all well and good. A little later, Callen claims that the identification of $$TdS$$ as the heat transfer is only...

Similar threads

Replies
28
Views
3K
Replies
4
Views
2K
Replies
7
Views
3K
Replies
2
Views
2K
Replies
7
Views
18K
Replies
9
Views
3K
Replies
4
Views
15K
Replies
6
Views
2K
Back
Top