Hi missdemeanor,
Thank you for your question.
Simply put, a block and tackle is an apparatus of pulley blocks and
ropes or cables used for hauling and hoisting heavy objects.
See demonstration on how it works by moving the green dots with your mouse at:
Block and Tackle
http://www.jimloy.com/cindy/block.htm
"On the left is a simple pulley, which changes the direction of the
force. On the right is the simplest block and tackle. These are
considered to be two of the "simple machines" (along with the wheel,
lever, inclined plane, wedge, and screw). The block and tackle that
you see here allows us to lift twice the weight with the same force as
with the simple pulley, but we only lift it half as far. A more
complicated block and tackle involves several of these simple block
and tackles, in one package deal."
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http://discover.edventures.com/functions/termlib.php?action=&termid=1669&alpha=b&searchString=
"A block and tackle is a tool often used to lift heavy or hard to
reach objects. It consists of two basic parts. The block is a pulley
or set of pulleys fitted in a frame. The block is usually attached to
a stationary object. The tackle is the rope or cable that runs through
the block and anything else needed to make the machine work. Some
tackles, like the one in the picture, use moving pulleys as well as
the rope. The rope will move through the block and, together, the
block and tackle can be used to help one person lift a lot more than
they could without it!"
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Block and Tackle image
http://www.bartleby.com/61/imagepages/A4blotac.html
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How a Block and Tackle Works
http://www.howstuffworks.com/pulley.htm
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Best regards,
tlspiegel |
