Julius Sumner Miller: Lesson 18 - How to Produce Heat Energy

There are many KINDS of ENERGY: Mechanical - Acoustic - Elec¬tric - Magnetic - Electrostatic - Chemical - Electromagnetic -
Atomic - Nuclear AND HEAT ENERGY. Strangely enough -
ALL of these can be transformed - transmuted - changed - into HEAT ENERGY. Indeed - all forms of energy do end up as heat energy! Physicists therefore refer to heat energy as a "degenerate" form.

A. Acid added to water is an exothermic process. Heat is evolved.
It is interesting to explore just why this occurs!

B. A cold cup of tea can be heated up - as we say - by stirring.
Mechanical energy is transformed into energy of motion of the
tea-stuff.

C. This cold cup of tea can be heated acoustically! Energy is required
for ordinary speech. Some people spend an awful amount of energy
just talking!! It is easy to calculate how much talk would be required to heat this cup of tea: Ordinary talk generates about TOO
ergs per second. This is about one ten-millionth watt.

D. We show an array of simple things:
1. Beat - hit - a sheet of lead with a hammer. It gets hot.
2. Beat a slab of lead with a hammer and a thermocouple imbedded in the lead block would show a rise in temperature.
3. Drive a nail into a block of wood. Pull it out. It is hot.
4. Drill a hard-wood block with an electric drill. The bit gets hot - the shavings get hot.
Here we make reference to Count Rumford - Sir Benjamin Thompson - in the 18th century - who was engaged in the boring of cannon - and his observations are a legacy to our understanding of HEAT.

E. A cardboard tube has some lead-shot in it. Let us first determine
the mass of the shot - the original temperature of the shot - the
length of the tube. Now what can we do? If we invert the tube
end-over-end the shot is now at the top of the tube and under
gravitation it falls down. Work is being done on it by gravitational forces. Its potential energy suffers conversion to kinetic. The impact forces generate heat. Now let us do this operation several
hundred times. We can therefore know the total height through which the shot falls. We can measure its final temperature. We thus can learn the Mechanical Equivalent of Heat. How much work does it take to produce so much heat!
F. Electrostatic energy can produce heat. The apparatus is called an
electrophorus. We rub or slap the lucite slab with a cat's fur.
This work separates the electric charges. We now place atop the
lucite slab a metal plate held by an insulating handle. We ground
the upper face of the metal plate. Now because of Coulomb forces
work is required to lift the plate from the slab. This work or energy
now resides in the form of electrostatic energy. A spark can be
drawn from the plate. This spark represents heat energy and light
energy . We can indeed "light" a fluorescent lamp with the new energy.
Which is an amazing thing indeed! And why is this so? Not certainly because we have a perpetual-motion machine.'.' Never that!
Never! The reason is this: that work is required to lift the plate
free of the charged slab.

G. As an interesting adventure: We show hot to extract a stubborn
glass stopper from a perfume bottle. Friction produces heat!