Chapter 8 Machines
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comp p uter sy y stems, , machines continue to help p us in both work and leisure
activities.
In the past few decades, computers have become much smaller and
“smarter.” At the same time, we have learned more about how humans
think and reason. This information has been combined to make
“intelligent” machines such as a robot that can vacuum the floor without
guidance. Intelligent machines are just beginning to be widely used,
but their possible uses are almost endless. Computer algorithms (sets
of programming rules) are allowing computers to make more and more
complex decisions.
What machines might people create in the next 50 years? How will
they compare to the machines and mechanisms included in this chapter?
You will have a part in deciding the answers to these questions. As you do,
be sure to keep in mind the responsibilities that go along with invention.
The machines created in this century and their effects on humans and the
environment will help shape the world you live in.
The six simple machines are the lever, pulley, wheel and axle, inclined
plane, wedge, and screw.
Gears are modified levers used in the transmission of rotary motion.
They can increase or decrease speed, change the direction of motion,
or transmit a force.
Pressure can be used to increase an effort applied. Pressure in liquids
is called hydraulics, and pressure in gases is called pneumatics.
Mechanisms change one kind of effort into another kind of effort. They
can be combined to form a machine. Machines change one kind of
energy into another kind and do work.
Friction results from resistance between the surfaces of moving parts.
Lubrication and other methods can be used to reduce friction and
increase the efficiency of machines.