Page 152 - DK Children's Encyclopedia

Machines SEE ALSO

▸ ▸ Aircraft p.13
▸ ▸ Bicycles p.36
Machines help us do things. They usually perform tasks ▸ ▸ Electricity p.87
that are too big, small, boring, long, or dangerous for ▸ ▸ Energy pp.88–89
people to do. Most modern machines are powered by ▸ ▸ Engines p.92

electricity or gas. ▸ ▸ Robots p.213

▸ ▸ Trains p.260

Simple machines
Simple machines reduce the
effort needed to do things.
A person must operate the
machine, but only a small
amount of effort is required
to move heavy objects. Pulley Wedge Screws
A pulley uses a rope or chain Made of wood or metal, this These sharp metal pins are used
looped over a wheel to lift triangular tool can be used to to attach things. As the screw is
heavy loads. push things apart. turned, it moves down and around.

The operator Big machines
sits in the
driver’s cabin. Backhoes are made up of
several simple machines.
They are powered by engines.

Lever
Levers move like
arms. This one
raises a metal
scoop to collect
building materials.
Wheel
Wheels make it easier to
move heavy things around.

Why we use
machines
Machines are usually
more efficient and
reliable than human
workers. This is because
they can do things
without ever becoming
bored, tired, slow,
or distracted. Neat work Repetitive work Dangerous work
A sewing machine can sew Automatic cash machines Robots are used to study active
more neatly and more quickly don’t sleep, so they can give volcanoes, so people do not have to
than most people can by hand. out money 24 hours a day. put themselves at risk.

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