Lesson 5 — Activity 1: Where Does Heat Come From?
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Lesson 5 — Activity 1: Where Does Heat Come From?
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Many ideas of where heat comes from were developed centuries ago. In this activity, you will learn about two important theories.
Theories of Heat
In the 1700s, a man named Count Rumford used observations about friction to help scientists learn about heat. (Friction theory had been around for centuries. It said that when two surfaces are rubbed together, the parts that touch resist movement. This resistance is friction.)
In the late 1700s, Count Rumford observed that heat was created when metal cut metal. This heat came from friction.
Rumford's thermodynamics experiment. [Photography]. Retrieved from Encyclopædia Britannica ImageQuest.
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https://quest.eb.com/search/132_1253634/1/132_1253634/cite
Rumford was an engineer and scientist who was hired to manufacture cannons in Germany. During this work, one worker touched a rod being used to bore a hole through a piece of metal. His hand was seriously burned, which led Rumford to developing a new theory about where heat comes from.
The modern theory of heat began in the 1800s with a man who was studying plants named Robert Brown.
When he was observing grains of pollen in a drop of water under a microscope, he noticed tiny particles moving around, even though the microscope was quite still. When he increased the temperature of the water, the jiggling motion increased.
This
jiggling motion became known as Brownian motion. At first, Brown
thought that the pollen grains were alive. Later, he figured out that
water must be composed of tiny unseen particles. These particles are in
constant, vibrating motion. The motion of the pollen grains must be
caused by collisions between the pollen grains and the other unseen
particles. Brown was unsure what the particles were.
Robert
Brown was the first to suggest that the energy that came with heat — or
thermal energy — was related to the jiggling motion of unseen particles
of a substance.
This
jiggling motion became known as Brownian motion. At first, Brown
thought that the pollen grains were alive. Later, he figured out that
water must be composed of tiny unseen particles. These particles are in
constant, vibrating motion. The motion of the pollen grains must be
caused by collisions between the pollen grains and the other unseen
particles. Brown was unsure what the particles were.
Robert Brown was the first to suggest that the energy that came with heat — or thermal energy — was related to the jiggling motion of unseen particles of a substance.
Robert Brown was the first to suggest that the energy that came with heat — or thermal energy — was related to the jiggling motion of unseen particles of a substance.
In the first theme of this course, you studied the particle theory of matter, which states the following:
• All matter is composed of tiny, unseen particles.
• These unseen particles are in constant, random motion.
Kinetic
means movement. Kinetic energy is a form of energy associated with
motion. Kinetic energy is a measure of the amount of motion particles
have.
(The
motion of particles can be compared to bumper cars you might see at an
amusement park. Like bumper cars, atoms and molecules collide with each
other at different speeds. All particles have different kinetic
energies.)
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