Question for people

[danceboy]

Is thermal mass equal to mass times a (units changing) constant? I.E. is the thermal mass of one 12 kg object equal to that of every other 12 kg object? I've asked a few people who I thought would know (chemical, civil, and mechanical engineers. No, I haven't been able to find a materials scientist.), and all of them said roughly "I think so. I mean, it sounds likely...."

Mind you I've forgotten why I cared in the first place, but care I do.

While we're on the subject of asking random questions; I don't understand what's going on with titanium in hammers and other impact tools (e.g. golf clubs).
I'm guessing that it's just marketing, but they're claiming that a similar sized Ti head will hit harder and be less work to swing. I believe that second part. I even believe that due to KE = 1/2mv^2 a titanium head will have more KE, but I think that inertia is the important thing here (by extrapolation to a dowel with a band of steel wrapped around the end to prevent splitting).

I can also see an advantage to a hammer that doesn't rust, and that doesn't get dinged up if you toss it into your tool box. Further, I think that giving Russia money right now is not a bad thing. I just don't really see a direct advantage for the hand holding the hammer.

Ideas? Comments?

Comments

some answers

[frobzwiththingz.livejournal.com]

Is thermal mass equal to mass times a (units changing) constant? I.E. is the thermal mass of one 12 kg object equal to that of every other 12 kg object?

No. "thermal mass" is really just another term for heat content, or "How many
Joules of heat energy are in the object", which could be stated roughly as "If you were to launch said object into deep space, how many Joules of energy would the object have lost when it cooled down?" (we'll ignore the 3 degree K
difference between absolute zero and space's background temperature).

Different substances have different "heat capacities". It takes a different amount of energy input to make 1 Kg of steel hotter by 1 degree, than 1 Kg of Aluminum. (about half as much, in fact). And it takes almost 10 times as much energy to heat up that same Kg of water that 1 degree. This is why you can quench red-hot steel in a small amount of water, and why you can use water to put out fires.

While we're on the subject of asking random questions; I don't understand what's going on with titanium in hammers and other impact tools (e.g. golf clubs).
I can't speak much for golf clubs, but for hammers it's almost certainly marketing. A pure titanium hammer would be pretty useless; Ti is much too brittle in its pure form to make a good hammer. So they've got to be using some sort of alloy. Whether it actually imparts more energy is going to depend mostly on who is swinging it. Just being a bit lighter isn't going to automatically mean you will end up swinging it that much faster than a steel one; thats going to depend more on your own swinging mechanics. Personally, as far as hammers go, its Estwing all the way for me, and none of that gimmicky anti-vibration stuff that the marketers have been trying lately.

Re: some answers

[goljerp]

Different substances have different "heat capacities". It takes a different amount of energy input to make 1 Kg of steel hotter by 1 degree, than 1 Kg of Aluminum. (about half as much, in fact). And it takes almost 10 times as much energy to heat up that same Kg of water that 1 degree.

Yes... (any excuse to haul out the CRC :-)

This is why you can quench red-hot steel in a small amount of water

Well, the thing about quenching steel in water is not just the heat capacity of the water, but also the fact that after you heat the water from room temperature (20 degrees C) to 100 degrees C, the water will boil, which accounts for a significant amount of energy transfer.