Chapter 8 Machines
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Friction may also be reduced in other ways. In the game of curling,
for example, “sweeping” the ice in front of the rock makes the rock travel
further and curl less. The heat from the sweeping action melts the ice,
creating a micro-thin layer of water on which the rock can ride. Sweeping
can increase the distance a rock travels by several feet. See Figure 8-63.
Lubrication
If you rub your hands together quickly, you will feel heat build up.
That heat is caused by friction. If your two hands were coated with oil,
friction would be reduced so they could more easily slide against one
another. Lubrication is the application of a smooth or slippery substance
between two objects to reduce friction.
gure 8-61. Hovercraft use a cushion of air
to reduce friction.
gure 8-62. One of the effects of streamlining
is to reduce air drag, which is a form of friction.
gure 8-63. Sweeping melts the
ice in front of the rock. Why does
this make the rock travel further?