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

[queen-of-wands.livejournal.com]

I don't have the proper background knowledge for your question to even make sense. But since nobody seems to be answering, I could post a link to your post from my journal. I find that I have the proper set of readers to answer questions ranging from "what has kink got to do with altered states of consciousness?" to "how can I preserve lots of aloe vera gel?" and knowing I've got scientists and mathematicians who have access to my journal, I bet someone among them has got your answers (although a large subset of these people have been unable to answer questions like "what's the word for history in the future?" so there is a limit to their cleverness).

[herooftheage.livejournal.com]

I don't think that "thermal mass" is a well defined physical term in the way you're looking for. Here's what Wikipedia says:

A thermal mass in the most general term refers to any mass used to absorb and hold heat. Materials with high specific heat like stone, concrete, adobe or water work best.

Specific heats vary for different substances, so in that sense, I'd answer your question as no, thermal masses of two 12 kg. objects are not necessarily the same.

---

What I am pretty sure is going on in golf clubs are clever attempts to deliver as much of the force to the ball through the impact zone as possible. Imagine a golf head made out of jello - it doesn't much matter how fast you get the thing moving, too much of the energy gets dissipated in the jello, not the golf ball. If "harder" means "less vibrations", then more of the energy gets spent on the impact.

Now the golf club case is particularly interesting, because the USGA claims designers have figured out how to make materials that rebound out a bit when hit - essentially turning the club face into a spring. I'm not sure I believe it, and the tests I've read about all seem to be tautological - clubs that hit the ball too far are deemed to have "rebound effect." Having looked at the tests, I don't see how they can tell if it is rebound effect of the clubhead, or if clubhead design deforms the ball differently for different heads, or something they haven't thought about. (Golf balls briefly deform on impact, and then go back to their normal shape. Obviously, a bit of energy goes into that deformation.)

The matter is further muddied by the amount of force transferred to the ball not being the only desiderata - how much spin you impart is a lot of the real key. The higher the spin on the ball, the straighter the ball travels, and the farther the effective distance, which is all golfers actually care about.

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.