My kids once rigged up a pulley to take their clean laundry upstairs. However, after they inched a basket up, they still had to walk up the stairs to put it away and were just as tired. Maybe if they'd studied how to use a pulley a bit more, they'd have tried it a little differently.
A pulley is one of the basic simple machines, those that harness physics so people can do more work than they could without them. How a pulley works seems really intuitive, until you examine them closely. Single pulleys will transfer work from down to up, but once you multiply them, they transfer work from weight to length. You can balance weight with two pulleys, but once you cross the ropes, you get different results.
James Orgill of The Action Lab (previously at Neatorama) shows us some of the weirder effects of a pulley. The weirdest is the floating table, which seems like a cool idea until someone bumps into a corner and your dinner goes flying. This video has a 65-second skippable ad at 2:00. -via Damn Interesting
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it seem to be a mistake made by the action lab guy. The "singe pully" is not a fix pully when one end is connected to your harness and the other end is pulled by your own hands. In this case the fixed pully acts as a loose pulley. Just compare the force that has to be exerted by the hands of a climber pulling himself up a fixed rope, with the situaton where the guy pulls himself up in the air with the pully. James Orgukk please correct.
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