[UK-CONTEST] Pulleys and rope

[Danny Higgins]

 From my distant memories of O Level mechanics:

The mechanical advantage of pulleys depends on how many you have and how 
they are connected.  If you loop the rope through 4 pulleys so that if 
you pull 10 feet of rope and the pulley block at the far end moves 2.5 
feet then you have a mechanical advantage of 4, i.e. the load you are 
trying to lift will seem a quarter of what it would have been if you 
didn't use a pulley.

Danny, G3XVR

gd0tep at safe-mail.net wrote:
> Ah... OK, I follow you now... but then I guess it depends on how many
> pullies you have within each block.
> Enough pullies, and it's easy(ish) to pull a system up using the way I do,
> whilst watching...
>
> But as I said, each to his own...
>
> Mind you, it wouldn't be the first time I've used a van to pull the rope as
> the system was A, tall, and B, heavy.
>
> Cheers...
> Andy
> http://gd0tep.com
>
>
> -----Original Message-----
> From: uk-contest-bounces at contesting.com
> [mailto:uk-contest-bounces at contesting.com]On Behalf Of Dave Lawley
> Sent: 10 July 2007 17:23
> To: UK Contest Reflector
> Subject: Re: [UK-CONTEST] Pulleys and rope
>
> Hi Andy
>
> You get the maximum mechanical advantage from the last sheave on the
> block only if you are pulling in line with the other ropes. That's hard
> to do with your arrangement.
>
> Cheers, Dave G4BUO
>
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