Physics Principles and Problems 2009Chapter 20:
Static ElectricityProblem of the Week <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/ch20_title.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | Deicing
Ice on an airplane is bad news. Less than a millimeter of ice
on top of the wing increases drag and reduces airplane lift
by 25%. A single airline company can spend tens of thousands
of dollars in a single day combating the grip of ice. |  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/ch20_deice.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (12.0K)</a>]]> | The
number of hazards that can be blamed on static electricity grows.  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/lilGuy.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]>
| The
Grip of Ice
In conditions below 32° F, ice sticks like a burr
to almost any surface. The cause of this stickiness is not unlike
paper bits sticking to a comb or plastic wrap clinging to a
bowl. Throughout the ice, molecules are randomly oriented with
regard to their electrical charge. At the surface, however,
molecules tend to line up in the same direction: primarily with
their protons facing out, or primarily with their protons facing
inward, buried in the ice. Either way, the surface of ice acquires
a net charge. When an electrically charged surface comes near
any other surface, the charged surface induces an opposite charge
in the facing surface and, because opposites attract, the two
surfaces are drawn together. This simple attraction accounts
for most of ice's adhesion. |  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/POWproblem1.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | Draw
a diagram explaining why ice is sticky. Use charged ovals,  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/dipole.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]>
(dipoles), to represent ice molecules. | | |  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/POWproblem2.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | A
Dartmouth physicist proposes to combat ice adhesion by applying
a small electrical charge to the surface. For airplanes, he
say it may be possible to prevent or significantly reduce ice
on the wings using a battery no bigger than the one in your
car. Explain how this might work. |  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/webLinks.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>]]> | Information
on aircraft icing can be obtained at http://www.aopa.org/asf/publications/sa11.html.
Clicking will launch a new window. |  <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/gutter.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/gutter.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> | <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078807220/193800/gutter.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (0.0K)</a>]]> |
|  |
|
