Name: tension in ropes and strings
Uploaded: 2025-05-22T09:06:17.000Z
Duration: 1 min 10 s
Channel: JoVE

张力被定义为与拉紧的绳子、绳索或电缆相关的力。它是一种拉力，因为张力只能拉动物体，而不能推动物体。
当绳子被拉紧时，张力通过绳子传递到所连接的物体上。此处，张力与物体的重力相平衡。
考虑一个质量为“m”的物体，在光滑表面上通过一根绳子以角度 theta 被拉动，并以加速度“a”运动。
在这种情况下，作用在箱子上的力包括向下的重力、向上的支持力以及沿拉绳方向的张力。
张力的 x 分量是唯一作用在水平方向上的力。
在竖直方向上，张力的 y 分量与支持力一同向上作用，而重力则向下作用。
将牛顿第二定律应用于该系统，可得到绳子施加的张力以及地面对箱子施加的法向力。

<ol>
	<li>OpenStax 的。（2019）. 大学物理学第 1 卷。[Web 版本]。取自 <a href="https://openstax.org/books/college-physics-2e/pages/4-5-normal-tension-and-other-examples-of-forces>https://openstax.org/books/college-physics-2e/pages/4-5-normal-tension-and-other-examples-of-forces</a></li>
</ol>

张力

张力是沿着介质长度的力，特别是由柔性介质（例如绳索或电缆）承载的力。 “张力”这个词来自拉丁语，意思是“伸展”。 并非巧合的是，将肌肉力量传递到身体其他部位的柔性绳索称为肌腱。 任何柔性连接器，例如细绳、绳索、链条、电线或电缆，只能在平行于其长度的方向上施加拉力； 因此，柔性连接器所承受的力是平行于连接器方向的张力。 重要的是要理解张力是连接器中的拉力。 假设这句话“你推不动绳子”； 拉力仅沿着绳子的两端向外拉。 柔性连接器通常用于在拐角处传递力，例如在医院牵引系统、指关节或自行车制动拉索中。 如果没有摩擦，张力就不会减弱地传递。 只是它的方向发生了变化，并且始终与柔性连接器平行。 例如，手指中的肌腱将力从肌肉传递到手指的其他部位，通常会改变力的方向，但不会改变力的大小。 肌腱相对无摩擦。 相同地，自行车上的制动拉索将张力从车把传递到制动机构。 同样，张力的方向发生了变化，但大小没有改变。

张力是沿介质长度方向作用的一种力，尤其指由绳索或电缆等柔性介质所传递的力。“张力”一词……

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Education

教育

JoVE Core

Mechanical Engineering

机械工程

Unit 1

第一单元

Physics Basics

物理基础

KEY TERMS AND CONCEPTS

关键术语与概念

Tension

tension in ropes and strings

Tension is the pulling force carried by a rope, string, or cable when it is stretched by a load. In physics, this force acts along the length of the object and pulls away from the objects at each end.

A stretched rope can support a hanging mass because the tension in the rope balances the weight of the load. The same idea appears in many everyday situations, such as a cable holding a sign or a string lifting an object.

Understanding tension helps students connect force diagrams to real motion. It also shows how forces are transmitted through flexible materials in simple systems.

Tension in Ropes and Strings

introduction to scalers

Scalar Quantities in Physics

Scalar quantities in physics have size only. They do not include direction. This makes them different from vector quantities. Common scalar examples include mass, temperature, time, and energy. Each one can be described with a number and a unit. Because direction is not part of the value, scalars are often easier to compare and measure.

vector or cross product

Cross Product of Two Vectors

The cross product of two vectors gives a new vector that is related to both original vectors. It is also called the vector product. In many physics problems, this operation helps describe quantities that depend on direction as well as size. The result of a cross product has a direction set by the two input vectors. It is not the same as ordinary multiplication. The transcript focuses on the vector or cross product as a core vector operation students use when working with vectors in science.

introduction to vectors

Vectors in Motion and Direction

Vectors describe quantities that have both size and direction. They are used in physics to show how motion, force, and other quantities act in space. A vector can be represented with an arrow. The length of the arrow shows the size, and the arrowhead shows the direction. This makes vectors useful for comparing how one quantity points relative to another. Scalars are different because they have size only and no direction. Understanding the difference between vectors and scalars is an important...

units and standards of measurement

Measurement Units, Standards, and SI Basics

Measurement units, standards, and SI basics help scientists describe physical quantities clearly. A unit gives a number meaning, while a standard provides a fixed reference for that measurement. Together, they make results easier to compare and understand. The International System of Units, or SI, is the most common measurement system in science. It uses agreed-upon base units for common quantities. These standards reduce confusion when measurements are shared across labs, classrooms, and...

accuracy and precision

Measurement Errors, Accuracy, and Precision

Measurement errors can affect how close a result is to the true value and how consistent repeated results are. Accuracy describes how close a measurement is to the accepted or true value. Precision describes how close repeated measurements are to one another. A result can be accurate, precise, both, or neither. A set of measurements may cluster tightly together and still be far from the true value. Another set may include values spread out from one another, even if one of them is close to the...

rules of significant figures

Counting Significant Figures in Measurements

Significant figures help students record measurements with the correct level of precision. They show which digits in a number are meaningful and which only help place the decimal point. In science class, this idea matters when writing and comparing measured values. The rules for significant figures explain how to count these digits in different numbers. Some digits are always counted, while others depend on where they appear in the number. Learning the rules makes it easier to report answers...

random and systematic errors

Measuring Error in Scientific Data

Random and systematic errors affect scientific measurements. Random errors cause values to spread around the true value. They make repeated measurements less consistent. Systematic errors shift measurements in the same direction each time. Understanding both kinds of error helps students judge data quality. Random error can come from small changes during measurement. Systematic error can come from a biased tool or method. Scientists look for these patterns so they can improve results and...

position and displacement

Tracking Motion with Position and Displacement

Position and displacement are key ideas in straight-line motion. Position tells where an object is located compared with a chosen starting point, called the origin. Displacement describes how far and in what direction the object has moved from its starting position. These ideas help describe motion clearly. Position can change as an object moves. Displacement focuses on the change in position, not just the path taken. That makes it useful for comparing motion in a simple and precise way.

position and displacement vectors

Using Vectors to Describe Motion

Position and displacement vectors describe motion in physics. A position vector shows where an object is located relative to a chosen origin. A displacement vector shows how far and in what direction the object moves from one point to another. These vectors are useful because they give a clear way to track movement in space. The video connects position and displacement to the idea of a reference point and shows how direction matters as much as distance. That makes them important for describing...

mass and weight

How Mass Differs from Weight

Mass and weight are related, but they are not the same. Mass is the amount of matter in an object. Weight is the force of gravity acting on that object. This difference matters because mass stays the same even when gravity changes. Weight can change if the gravitational pull changes. A person or object therefore has the same mass, but not always the same weight. The terms are often used in everyday speech as if they mean the same thing. In physics, they describe two different ideas.

acceleration due to gravity on earth

Free-Fall Acceleration on Earth

Free-fall acceleration on Earth describes how fast an object speeds up when gravity is the only force acting on it. Near Earth’s surface, this acceleration is nearly constant for many everyday situations. Gravity pulls objects toward Earth and gives them downward acceleration. This motion is often written as g, and it helps explain why falling objects gain speed as they move downward. The value of g is commonly used in physics to predict the motion of objects dropped or released near the...

tension

Tension is the pulling force carried by a rope, string, or cable when it is stretched by a load. In physics, this force acts along the length of the object and pulls away from the objects at each end. A stretched rope can support a hanging mass because the tension in the rope balances the weight of the load. The same idea appears in many everyday situations, such as a cable holding a sign or a string lifting an object. Understanding tension helps students connect force diagrams to real motion.

gravitational force

How Gravity Acts Between Objects

Gravity is a force that pulls objects toward one another. On Earth, this force gives objects weight and keeps people, water, and other materials from drifting away. It also helps explain why planets and moons stay in motion around larger bodies. The strength of gravitational force depends on the masses of the objects involved. Larger masses create a stronger pull, while smaller masses create a weaker one. The distance between objects also matters, because gravity becomes weaker as objects move...

key terms and concepts

Learn how tension acts in ropes, strings, and cables as a pulling force that supports loads and balances weight in everyday physics examples.

Tension in Ropes and Strings | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

Tension in Ropes and Strings

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