Pulley - Revision history

Jmdonev: 1 revision imported

2021-09-27T00:02:59Z

1 revision imported

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energy>Ethan.boechler at 18:01, 10 September 2021

2021-09-10T18:01:26Z

← Older revision		Revision as of 18:01, 10 September 2021
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	[[Category:3A_Energy_A_closer_look]]		[[Category:3A_Energy_A_closer_look]]
	[[Category:371_topics]]		[[Category:371_topics]]
			[[Category: Translated to French]]
			[[fr:Poulie]]
	[[File:Boat-215039 640.jpg\|250px\|thumbnail\|Figure 1: A pulley being used on a boat, consisting of a metal wheel and a rope.<ref>Pixabay [Online], Available: http://pixabay.com/p-215039/?no_redirect</ref>]]		[[File:Boat-215039 640.jpg\|250px\|thumbnail\|Figure 1: A pulley being used on a boat, consisting of a metal wheel and a rope.<ref>Pixabay [Online], Available: http://pixabay.com/p-215039/?no_redirect</ref>]]
	<onlyinclude>A '''pulley''' is a [[simple machine]] that can change the magnitude and direction of an applied [[force]] in the process of doing [[work]]. It consists of a cable which is attached to a [[wheel and axle]], and is often used to lift/transport objects. When referred to in this context, these objects that are being moved are generally known as the '''load'''.</onlyinclude> Figure 1 shows a simple pulley but pulleys often work together in systems; figure 2 shows examples of pulley systems.		<onlyinclude>A '''pulley''' is a [[simple machine]] that can change the magnitude and direction of an applied [[force]] in the process of doing [[work]]. It consists of a cable which is attached to a [[wheel and axle]], and is often used to lift/transport objects. When referred to in this context, these objects that are being moved are generally known as the '''load'''.</onlyinclude> Figure 1 shows a simple pulley but pulleys often work together in systems; figure 2 shows examples of pulley systems.

Jmdonev: 1 revision imported

2017-08-29T01:47:23Z

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Jmdonev at 22:19, 16 August 2017

2017-08-16T22:19:50Z

← Older revision		Revision as of 22:19, 16 August 2017
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	[[Category:Done ~~2015~~-04-01]] [[Category:3A_Energy_A_closer_look]]		[[Category:Done 2017-07-01]]
			[[Category:3A_Energy_A_closer_look]]
	[[Category:371_topics]]		[[Category:371_topics]]
	[[File:Boat-215039 640.jpg\|~~200px~~\|thumbnail\|Figure 1: A pulley being used on a boat, consisting of a metal wheel and a rope.<ref>Pixabay [Online], Available: http://pixabay.com/p-215039/?no_redirect</ref>]]		[[File:Boat-215039 640.jpg\|250px\|thumbnail\|Figure 1: A pulley being used on a boat, consisting of a metal wheel and a rope.<ref>Pixabay [Online], Available: http://pixabay.com/p-215039/?no_redirect</ref>]]
	<onlyinclude>A '''pulley''' is a [[simple machine]] that can change the magnitude and direction of an applied [[force]] in the process of doing [[work]]. It consists of a cable which is attached to a [[wheel and axle]], and is often used to lift/transport objects. When referred to in this context, these objects that are being moved are generally known as the '''load'''.</onlyinclude> Figure 1 shows a simple pulley but pulleys often work together in systems; figure 2 shows examples of pulley systems.		<onlyinclude>A '''pulley''' is a [[simple machine]] that can change the magnitude and direction of an applied [[force]] in the process of doing [[work]]. It consists of a cable which is attached to a [[wheel and axle]], and is often used to lift/transport objects. When referred to in this context, these objects that are being moved are generally known as the '''load'''.</onlyinclude> Figure 1 shows a simple pulley but pulleys often work together in systems; figure 2 shows examples of pulley systems.

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	Pulleys use the concept of [[mechanical advantage]], which shows how much an applied force is a multiplied (and the distance that force moves decreases). For pulleys, the ideal mechanical advantage is		Pulleys use the concept of [[mechanical advantage]], which shows how much an applied force is a multiplied (and the distance that force moves decreases). For pulleys, the ideal mechanical advantage is

	<m>IMA=N</m>,		<math>IMA=N</math>,
	where <m>N</m> is the number of fixed-axis pulleys.<ref>Hyperphysics, ''Simple Machines'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/lever.html</ref>		where <math>N</math> is the number of fixed-axis pulleys.<ref>Hyperphysics, ''Simple Machines'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/lever.html</ref>

	For example, if the mechanical advantage of a pulley system is 3, the pulley system has 3 fixed pulleys acting on an object, therefore reducing the force that needs to be applied by a factor of 3. Due to the rules of [[conservation of energy]] however, the distance that this force needs to act over is three times the distance that the load will actually move. This comes from the idea that [[work]] is force times distance, this means that W<sub>in</sub> = W<sub>out</sub>.		For example, if the mechanical advantage of a pulley system is 3, the pulley system has 3 fixed pulleys acting on an object, therefore reducing the force that needs to be applied by a factor of 3. Due to the rules of [[conservation of energy]] however, the distance that this force needs to act over is three times the distance that the load will actually move. This comes from the idea that [[work]] is force times distance, this means that W<sub>in</sub> = W<sub>out</sub>.

J.williams: 1 revision imported

2015-08-26T21:31:34Z

1 revision imported

← Older revision	Revision as of 21:31, 26 August 2015
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J.williams at 16:58, 12 August 2015

2015-08-12T16:58:44Z

New page

[[Category:Done 2015-04-01]] [[Category:3A_Energy_A_closer_look]]
[[Category:371_topics]]
[[File:Boat-215039 640.jpg|200px|thumbnail|Figure 1: A pulley being used on a boat, consisting of a metal wheel and a rope.<ref>Pixabay [Online], Available: http://pixabay.com/p-215039/?no_redirect</ref>]]
<onlyinclude>A '''pulley''' is a [[simple machine]] that can change the magnitude and direction of an applied [[force]] in the process of doing [[work]]. It consists of a cable which is attached to a [[wheel and axle]], and is often used to lift/transport objects. When referred to in this context, these objects that are being moved are generally known as the '''load'''.</onlyinclude> Figure 1 shows a simple pulley but pulleys often work together in systems; figure 2 shows examples of pulley systems.

==Mechanical advantage in pulleys==
Pulleys use the concept of [[mechanical advantage]], which shows how much an applied force is a multiplied (and the distance that force moves decreases). For pulleys, the ideal mechanical advantage is

<m>IMA=N</m>,
where <m>N</m> is the number of fixed-axis pulleys.<ref>Hyperphysics, ''Simple Machines'' [Online], Available: http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/lever.html</ref>

For example, if the mechanical advantage of a pulley system is 3, the pulley system has 3 fixed pulleys acting on an object, therefore reducing the force that needs to be applied by a factor of 3. Due to the rules of [[conservation of energy]] however, the distance that this force needs to act over is three times the distance that the load will actually move. This comes from the idea that [[work]] is force times distance, this means that W<sub>in</sub> = W<sub>out</sub>.

The pulleys in Figure 2 illustrate what creates this mechanical advantage; the tension of the ropes. The load is pulling down on the centre of the pulley which is supported by cables or ropes. Therefore the force of the load is distributed evenly among the cables. For the case of two pulleys (the second pulley in Figure 3), the force of this object is distributed to only two cables, therefore yielding a mechanical advantage of 2. It can be seen from the other systems that this principle applies more so as more pulleys are added.

[[File:Picture2.png|700px|thumbnail|center|Figure 2: Four pulleys with different mechanical advantages.<ref>Wikimedia Commons [Online], Available: http://upload.wikimedia.org/wikipedia/commons/e/e9/Four_pulleys.svg</ref>]]

It is important to understand that although the force is decreased using these systems, this doesn't change the amount of work done. Another important thing to remember is that these are ''ideal systems''; the cable and pulleys masses are neglected, and there are only [[conservative force]]s acting on the system. In reality these objects have masses, and there are many energy losses due to [[friction]] and [[sound]].

==References==
{{reflist}}
[[Category:Uploaded]]