How does a pulley make work easier if it doesn't multiply??
2007-09-25 16:44:38 · 5 answers · asked by Mwahahah!! 1 in Science & Mathematics ➔ Other - Science
Strictly speaking, a multiple pulley system doesn't reduce the total amount of work. It may even increase the work you have to do, by adding extra friction. However, just like a ramp is easier than lifting straight up, using a series of pulleys means the amount of force you need to apply is reduced. So, instead of having to pull a 1000 lb load up five feet, you might have to pull 25 feet of rope with 200 lbs of force.
2007-09-26 03:26:08 · answer #1 · answered by Dvandom 6 · 0⤊ 0⤋
Thanks for asking this question - I've always wondered too...
From Encarta - "The pulley is one of the four simple machines (along with the lever, the wheel and axle, and the inclined plane) used to do work. Work is defined in physics as the result of a force, such as the effort of pulling on a rope, that moves an object across a distance. Pulleys reduce the effort to lift an object by increasing the distance over which the effort is applied."
"A single fixed pulley changes the direction of the force applied to the end of the rope. A common example of a pulley can be found at the top of a flagpole. Pulling down on the rope causes the flag to go up because the pulley changes the direction of the force applied to the flag. Multiple pulleys can change both the direction of the applied force and the amount of force, so that less force is needed to lift an object. Construction cranes use multiple pulley systems to reduce the amount of force needed to lift heavy equipment."
Aha!
2007-09-25 23:53:47 · answer #2 · answered by Anonymous · 0⤊ 0⤋
It lets you change the direction of a force with nearly zero cost (friction). You can use your weight to lift something you couldn't lift with just your muscle. You can lift the box and make fast the rope to a cleat and leave it there all day with no effort. The bucket can be lifted by someone (or a team) safely on the ground instead of atop a rickety scaffold.
You could have gotten this and more, just by thinking. Why did you ask here? That's why it was such a good question.
2007-09-25 23:54:29 · answer #3 · answered by Frank N 7 · 0⤊ 0⤋
It makes it easier by letting you do the work in the DIRECTION that is easiest for you, while applying that work in whatever other direction is actually needed.
2007-09-26 09:12:52 · answer #4 · answered by bh8153 7 · 1⤊ 0⤋
it does multiply. it makes your rope(which is a lever)longer.
the longer the lever the more weight it can lift
2007-09-25 23:56:16 · answer #5 · answered by xanie k 1 · 1⤊ 2⤋