Tension: Difference between revisions

Revision as of 01:57, 30 November 2015

claimed by Jae Hee Kim (chloejhkim)

This topic covers Tension.

What is Tension?

The tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends. The tension force is directed along the length of the wire and pulls equally on the objects on the opposite ends of the wire.

Ropes and cables are useful for exerting forces since they can efficiently transfer a force over a significant distance (e.g. the length of the rope). For instance, a sled can be pulled by a team of Siberian Huskies with ropes secured to them which lets the dogs run with a larger range of motion compared to requiring the Huskies to push on the back surface of the sled from behind using the normal force. (Yes, that would be the most pathetic dog sled team ever.) It's important to note here that tension is a pulling force since ropes simply can't push effectively. Trying to push with a rope causes the rope to go slack and lose the tension that allowed it to pull in the first place. This might sound obvious, but when it comes time to draw the forces acting on an object, people often draw the force of tension going in the wrong direction so remember that tension can only pull on an object.

How To Calculate Tension Force

we use Newton's second law to relate the motion of the object to the forces involved. To be specific we can, Draw the forces exerted on the object in question. Write down Newton's second law (a=\dfrac{\Sigma F}{m})(a= m ΣF ) for a direction in which the tension is directed. Solve for the tension using the Newton's second law equation a=\dfrac{\Sigma F}{m}a= m ΣF . We'll use this problem solving strategy in the solved examples below.

Example Problem

Example 1: Angled rope pulling on a box

A 2.0 \text{ kg}2.0 kg2, point, 0, space, k, g box of cucumber extract is being pulled across a frictionless table by a rope at an angle \theta=60^oθ=60 o theta, equals, 60, start superscript, o, end superscript as seen below. The tension in the rope causes the box to slide across the table to the right with an acceleration of 3.0\dfrac{\text{m}}{\text{ s}^2}3.0 s 2 m 3, point, 0, start fraction, m, divided by, space, s, start superscript, 2, end superscript, end fraction.

What is the tension in the rope?

First we draw a force diagram of all the forces acting on the box.

Now we use Newton's second law. The tension is directed both vertically and horizontally, so it's a little unclear which direction to choose. However, since we know the acceleration horizontally, and since we know tension is the only force directed horizontally, we'll use Newton's second law in the horizontal direction. a x = m ΣF x (use Newtons's second law for the horizontal direction) 3.0\dfrac{\text{m}}{\text{ s}^2}=\dfrac{\purpleD {T} \text{cos}60^o}{2.0\text{ kg}} \quad \text{(plug in the horizontal acceleration, mass, and horizontal forces)}3.0 s 2 m = 2.0 kg Tcos60 o (plug in the horizontal acceleration, mass, and horizontal forces)

Middling

Difficult

Connectedness

How is this topic connected to something that you are interested in?
How is it connected to your major?
Is there an interesting industrial application?

History

Put this idea in historical context. Give the reader the Who, What, When, Where, and Why.

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 claimed by Jae Hee Kim (chloejhkim)
-Contents [hide]
+This topic covers Tension.
-Thermodynamics
-.1 Zeroth Law
-.1.1 A Mathematical Model
-.1.2 A Computational Model
-.2 First Law
-.2.1 A Mathematical Model
-Second Law
-.1 Mathematical Models
-.2 Examples
-Connectedness
-History
-See also
-.1 Further reading
-.2 External links
-References
-Thermodynamics[edit]
-This topics focuses on energy work of a system but it can only deal with a large scale response to heat in a system. Thermodynamics is the study of the work, heat and energy of a system. The smaller scale gas interactions can explained using the kinetic theory of gases. There are three fundamental laws that go along with the topic of thermodynamics. They are the zeroth law, the first law, and the second law. These laws help us understand predict the the operation of the physical system. In order to understand the laws, you must first understand thermal equilibrium. Thermal equilibrium is reached when a object that is at a higher temperature is in contact with an object that is at a lower temperature and the first object transfers heat to the latter object until they approach the same temperature and maintain that temperature constantly. It is also important to note that any thermodynamic system in thermal equilibrium possesses internal energy.
-Zeroth Law[edit]
+== What is Tension? ==
-The zeroth law states that if two systems are at thermal equilibrium at the same time as a third system, then all of the systems are at equilibrium with each other. If systems A and C are in thermal equilibrium with B, then system A and C are also in thermal equilibrium with each other. There are underlying ideas of heat that are also important. The most prominent one is that all heat is of the same kind. As long as the systems are at thermal equilibrium, every unit of internal energy that passes from one system to the other is balanced by the same amount of energy passing back. This also applies when the two systems or objects have different atomic masses or material.
+The tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends. The tension force is directed along the length of the wire and pulls equally on the objects on the opposite ends of the wire.
-A Mathematical Model[edit]
+Ropes and cables are useful for exerting forces since they can efficiently transfer a force over a significant distance (e.g. the length of the rope). For instance, a sled can be pulled by a team of Siberian Huskies with ropes secured to them which lets the dogs run with a larger range of motion compared to requiring the Huskies to push on the back surface of the sled from behind using the normal force. (Yes, that would be the most pathetic dog sled team ever.)
-If A = B and A = C, then B = C A = B = C
+It's important to note here that tension is a pulling force since ropes simply can't push effectively. Trying to push with a rope causes the rope to go slack and lose the tension that allowed it to pull in the first place. This might sound obvious, but when it comes time to draw the forces acting on an object, people often draw the force of tension going in the wrong direction so remember that tension can only pull on an object.
-A Computational Model[edit]
+=== How To Calculate Tension Force ===
-How do we visualize or predict using this topic. Consider embedding some vpython code here Teach hands-on with GlowScript
-First Law[edit]
+we use Newton's second law to relate the motion of the object to the forces involved. To be specific we can,
-The first law of thermodynamics defines the internal energy (E) as equal to the difference between heat transfer (Q) into a system and work (W) done by the system. Heat removed from a system would be given a negative sign and heat applied to the system would be given a positive sign. Internal energy can be converted into other types of energy because it acts like potential energy. Heat and work, however, cannot be stored or conserved independently because they depend on the process. This allows for many different possible states of a system to exist. There can be a process known as the adiabatic process in which there is no heat transfer. This occurs when a system is full insulated from the outside environment. The implementation of this law also brings about another useful state variable, enthalpy.
+Draw the forces exerted on the object in question.
+Write down Newton's second law (a=\dfrac{\Sigma F}{m})(a=
+m
+ΣF
+ ) for a direction in which the tension is directed.
+Solve for the tension using the Newton's second law equation a=\dfrac{\Sigma F}{m}a=
+m
+ΣF
+ .
+We'll use this problem solving strategy in the solved examples below.
-A Mathematical Model[edit]
+== Example Problem ==
-E2 - E1 = Q - W
-Second Law[edit]
+=== Example 1: Angled rope pulling on a box ===
-The second law states that there is another useful variable of heat, entropy (S). Entropy can be described as the disorder or chaos of a system, but in physics, we will just refer to it as another variable like enthalpy or temperature. For any given physical process, the combined entropy of a system and the environment remains a constant if the process can be reversed. The second law also states that if the physical process is irreversible, the combined entropy of the system and the environment must increase. Therefore, the final entropy must be greater than the initial entropy.
+A 2.0 \text{ kg}2.0 kg2, point, 0, space, k, g box of cucumber extract is being pulled across a frictionless table by a rope at an angle \theta=60^oθ=60
+o
+ theta, equals, 60, start superscript, o, end superscript as seen below. The tension in the rope causes the box to slide across the table to the right with an acceleration of 3.0\dfrac{\text{m}}{\text{ s}^2}3.0
+ s
+m
+, point, 0, start fraction, m, divided by, space, s, start superscript, 2, end superscript, end fraction.
-Mathematical Models[edit]
+'''What is the tension in the rope?'''
-delta S = delta Q/T Sf = Si (reversible process) Sf > Si (irreversible process)
-Examples[edit]
+First we draw a force diagram of all the forces acting on the box.
-Reversible process: Ideally forcing a flow through a constricted pipe, where there are no boundary layers. As the flow moves through the constriction, the pressure, volume and temperature change, but they return to their normal values once they hit the downstream. This return to the variables' original values allows there to be no change in entropy. It is often known as an isentropic process.
-Irreversible process: When a hot object and cold object are put in contact with each other, eventually the heat from the hot object will transfer to the cold object and the two will reach the same temperature and stay constant at that temperature, reaching equilibrium. However, once those objects are separated, they will remain at that equilibrium temperature until something else acts upon it. The objects do not go back to their original temperatures so there is a change in entropy.
+Now we use Newton's second law. The tension is directed both vertically and horizontally, so it's a little unclear which direction to choose. However, since we know the acceleration horizontally, and since we know tension is the only force directed horizontally, we'll use Newton's second law in the horizontal direction.
+a
+x
+ =
+m
+ΣF
+x
+ (use Newtons's second law for the horizontal direction)
+.0\dfrac{\text{m}}{\text{ s}^2}=\dfrac{\purpleD {T} \text{cos}60^o}{2.0\text{ kg}} \quad \text{(plug in the horizontal acceleration, mass, and horizontal forces)}3.0
+ s
+m
+ =
+.0 kg
+Tcos60
+o
+ (plug in the horizontal acceleration, mass, and horizontal forces)
+===Middling===
+===Difficult===
-Connectedness[edit]
+==Connectedness==
-How is this topic connected to something that you are interested in?
+#How is this topic connected to something that you are interested in?
-How is it connected to your major?
+#How is it connected to your major?
-Is there an interesting industrial application?
+#Is there an interesting industrial application?
-History[edit]
-Thermodynamics was brought up as a science in the 18th and 19th centuries. However, it was first brought up by Galilei, who introduced the concept of temperature and invented the first thermometer. G. Black first introduced the word 'thermodynamics'. Later, G. Wilke introduced another unit of measurement known as the calorie that measures heat. The idea of thermodynamics was brought up by Nicolas Leonard Sadi Carnot. He is often known as "the father of thermodynamics". It all began with the development of the steam engine during the Industrial Revolution. He devised an ideal cycle of operation. During his observations and experimentations, he had the incorrect notion that heat is conserved, however he was able to lay down theorems that led to the development of thermodynamics. In the 20th century, the science of thermodynamics became a conventional term and a basic division of physics. Thermodynamics dealt with the study of general properties of physical systems under equilibrium and the conditions necessary to obtain equilibrium.
-See also[edit]
+==History==
-Are there related topics or categories in this wiki resource for the curious reader to explore? How does this topic fit into that context?
+Put this idea in historical context. Give the reader the Who, What, When, Where, and Why.
+== See also ==
+Are there related topics or categories in this wiki resource for the curious reader to explore?  How does this topic fit into that context?
+===Further reading===
-Further reading[edit]
 Books, Articles or other print media on this topic
-External links[edit]
+===External links===
 Internet resources on this topic
-References[edit]
+==References==
-https://www.grc.nasa.gov/www/k-12/airplane/thermo0.html http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thereq.html https://www.grc.nasa.gov/www/k-12/airplane/thermo2.html http://www.phys.nthu.edu.tw/~thschang/notes/GP21.pdf http://www.eoearth.org/view/article/153532/
+This section contains the the references you used while writing this page
+[[Category:Which Category did you place this in?]]

Tension: Difference between revisions

Revision as of 01:57, 30 November 2015

What is Tension?

How To Calculate Tension Force

Example Problem

Example 1: Angled rope pulling on a box

Middling

Difficult

Connectedness

History

See also

Further reading

External links

References

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