In article <20031008202828.30810.qmail@web60207.mail.yahoo.com>,
Tim <Use-Author-Address-Header@[127.1]> wrote:

A physics puzzle:

I have a computer and a spaceheater with the same
wattage.

Would they heat up a room equally as much?

HINT: the law of conservation of energy

Depends on whether it's hooked up to the internet,

how well it is EM
shielded, and whether you print anything. Are the shades down?

In article <20031008202828.30810.qmail@web60207.mail.yahoo.com>,
Tim <Use-Author-Address-Header@[127.1]> wrote:

A physics puzzle:
I have a computer and a spaceheater with the same
wattage.
Would they heat up a room equally as much?

Not necessarily. Although the the computer and the space heater
will consume the same wattage and thus release the same amount
of energy, not all of the energy will be in the form of heat.
Presumably the space heater will be mostly infra-red, but the
computer will emit some radio waves and a certain amount of noise
which, since they will likely escape the room, will not contribute
to heating the room.

Okay, explain why I'm wrong.

In sci.physics, Tim
<Use-Author-Address-Header@[>
wrote
on Wed, 8 Oct 2003 13:28:28 -0700 (PDT)
<20031008202828.30810.qmail@web60207.mail.yahoo.com>:

A physics puzzle:

I have a computer and a spaceheater with the same
wattage.

Would they heat up a room equally as much?

HINT: the law of conservation of energy

The short answer is no, as the computer is a maximum
rating, and may consume far less power, especially using
Linux and sitting idle. :-) (There's currently no way
around the heating of the disk drive, though.)

Assume a 4m x 4m x 2.5m room and 40 moles/m^3 x 40 m^3 = 1600 moles
or 44.8 kg of nitrogen. (If you want a more precise result
use the Guy-Lussac law.) K = 300; presumably this means that
29.12 * 300 * 1600 J = 13977600 J is required to heat that
gas 1 degree C.

http://www.webelements.com/webelements/elements/text/N/thdyn.html

Running that 300 W heater for a full day, assuming perfect
insulation, will raise the temperature 300 * 86400 / 13977600
= 1.85 degrees.

Unfortunately, thermodynamics isn't my strong point so my
computations could be way off. :-) And in any event the
most important issue is keeping one's feet warm... :-)

[.sigsnip]

Tim <Use-Author-Address-Header@[127.1]> wrote:

A physics puzzle:

I have a computer and a spaceheater with the same
wattage.

Would they heat up a room equally as much?

No. The wattage spec for the computer is a maximum power
rating for the draw on the power cord. The wattage of
the space-heater is the wattage it draws nominally.

Any cute answer involving the energy stored in the
information processed by the computer falls well below the
noise floors for both devices and possibly below the energy
added to your room by the cosmic background radiation.

HINT: the law of conservation of energy

Does not apply on Usenet.

--Blair
"So many flames; so little warmth."

Tim <Use-Author-Address-Header@[127.1]> wrote:

I have a computer and a spaceheater with the same wattage.

Would they heat up a room equally as much?

Actually, the room noticably hotter when the laptop's been running
long enough. It's even worse now that the fan doesn't function anymore.
The heat goes into the keyboard, which inevitably gets nearly too hot
too touch or even put the hands near.

Tim <Use-Author-Address-Header@[127.1]> wrote:

I have a computer and a spaceheater with the same wattage.

Would they heat up a room equally as much?

Actually, the room noticably hotter when the laptop's been running
long enough. It's even worse now that the fan doesn't function anymore.
The heat goes into the keyboard, which inevitably gets nearly too hot
too touch or even put the hands near.