Simple Machines B/Compound Machines C Question Marathon

[craydraygon]

This is how I understand Mechanical Advantage vs. Mechanical Disadvantage in pulleys:

A pulley system is "reeved" to disadvantage when the end part of the rope goes through a pulley that does not add a mechanical advantage but only friction. So this is when the rope that you are pulling is coming directly off of a fixed pulley. For example, a pulley system with one movable pulley has a mechanical advantage of two, and a pulley system with one fixed and one movable pulley also has a mechanical advantage of two. In the system with two pulleys however, the extra pulley causes extra friction which means it is reeved to disadvantage.

So I don't believe any pulley system can have an IMA less than one (however it can have an AMA less than one).

Here's the website that I learned this from: http://efclimbers.net/wp-content/upload ... +Paper.pdf

hope this all makes sense!

[Algorhythmic]

Thanks for the help!

[JustDroobles]

This is how I understand Mechanical Advantage vs. Mechanical Disadvantage in pulleys:

A pulley system is "reeved" to disadvantage when the end part of the rope goes through a pulley that does not add a mechanical advantage but only friction. So this is when the rope that you are pulling is coming directly off of a fixed pulley. For example, a pulley system with one movable pulley has a mechanical advantage of two, and a pulley system with one fixed and one movable pulley also has a mechanical advantage of two. In the system with two pulleys however, the extra pulley causes extra friction which means it is reeved to disadvantage.

So I don't believe any pulley system can have an IMA less than one (however it can have an AMA less than one).

Here's the website that I learned this from: http://efclimbers.net/wp-content/upload ... +Paper.pdf

hope this all makes sense!

A pulley system can have an IMA of less than 1, but the force does not necessarily need to be applied to a string. In any pulley system, if you switch the input and output forces, you will get the reciprocal IMA. For example, if you look at the first page of your link, there is a pulley system with IMA of 4. If instead you attached the load to the "original input" string, and applied the force where the current load is, (pulling on the string attached to the bottom pulley) you would have a pulley system with an IMA of 1/4.

[craydraygon]

This is how I understand Mechanical Advantage vs. Mechanical Disadvantage in pulleys:

A pulley system is "reeved" to disadvantage when the end part of the rope goes through a pulley that does not add a mechanical advantage but only friction. So this is when the rope that you are pulling is coming directly off of a fixed pulley. For example, a pulley system with one movable pulley has a mechanical advantage of two, and a pulley system with one fixed and one movable pulley also has a mechanical advantage of two. In the system with two pulleys however, the extra pulley causes extra friction which means it is reeved to disadvantage.

So I don't believe any pulley system can have an IMA less than one (however it can have an AMA less than one).

Here's the website that I learned this from: http://efclimbers.net/wp-content/upload ... +Paper.pdf

hope this all makes sense!

A pulley system can have an IMA of less than 1, but the force does not necessarily need to be applied to a string. In any pulley system, if you switch the input and output forces, you will get the reciprocal IMA. For example, if you look at the first page of your link, there is a pulley system with IMA of 4. If instead you attached the load to the "original input" string, and applied the force where the current load is, (pulling on the string attached to the bottom pulley) you would have a pulley system with an IMA of 1/4.

Aahhh I see. Thank you, I hadn't thought about mechanical advantage that way.