Name: forces inside a body and balance
Uploaded: 2023-09-22T11:49:22.000Z
Duration: 1 min 25 s
Channel: JoVE

Internal forces are generated within a body due to the interaction between its particles. These forces include tension, compression, and shear.&#160;
The internal forces exist in collinear pairs of equal magnitude but opposite directions. They cancel out between all the connected parts, resulting in the body&#39;s equilibrium.
The weight of a body is an external force represented by a single resultant force acting through the body&#39;s center of gravity.
It is the point where a body balances itself, provided no external force acts on it.
A symmetrical or uniform body has its center of gravity at its geometric center. However, for an irregular or non-uniform body, it is off-centered towards the heavier side.
Consider a beam attached to a crane at the center, with loads connected at its ends. If load on one side becomes heavy, the center of gravity will shift away from the centerline of the beam, potentially causing tipping.
The center of gravity must be identified to ensure stability, and the lifting hook should be placed directly above it.

interne krachten en het zwaartepunt

Internal Forces and Center of Gravity

Interne krachten en het zwaartepunt zijn fundamentele concepten in de mechanica, die een cruciale rol spelen bij het begrijpen van het gedrag en de stabiliteit van structuren en objecten onder verschillende omstandigheden. Een grondig begrip van deze principes is essentieel voor ingenieurs, architecten en ontwerpers om veilige en efficiënte systemen te creëren. Interne krachten worden gegenereerd binnen een lichaam als gevolg van de interactie tussen de deeltjes ervan. Deze krachten kunnen worden ingedeeld in trekkracht, drukkracht en schuifkracht. Deze interne krachten bestaan uit collineaire paren met een gelijke grootte maar tegengestelde richtingen. Ze heffen elkaar op tussen alle verbonden delen, waardoor het lichaam in evenwicht blijft. Het gewicht van een lichaam is een externe kracht, die wordt vertegenwoordigd door een enkele resultante kracht die door het zwaartepunt van het lichaam werkt. Het zwaartepunt is het punt waarop een lichaam in evenwicht blijft wanneer er geen externe kracht op werkt. Het zwaartepunt bevindt zich op het geometrische centrum voor symmetrische of gelijkmatige lichamen. Het zwaartepunt kan echter uit het midden liggen en naar de zwaardere kant verschoven zijn voor onregelmatige of ongelijkmatige lichamen. Het begrijpen van interne krachten en het zwaartepunt is cruciaal voor het analyseren en handhaven van de stabiliteit en het evenwicht van verschillende structuren en objecten. Bijvoorbeeld, in de civiele techniek worden deze principes gebruikt bij het ontwerpen van bruggen, gebouwen en andere infrastructuur die bestand moet zijn tegen externe krachten zoals wind, aardbevingen en verkeersbelastingen. In de werktuigbouwkunde wordt de kennis van interne krachten en het zwaartepunt toegepast bij het ontwerpen van machines, voertuigen en andere mechanische systemen die veilig en efficiënt kunnen werken onder verschillende belastingen en omstandigheden. Bij de lucht- en ruimtevaart is het nauwkeurig bepalen van het zwaartepunt van vliegtuigen en ruimtevaartuigen van vitaal belang voor het waarborgen van stabiliteit en controle tijdens de vlucht. Een verschuiving in het zwaartepunt kan ernstige gevolgen hebben voor de prestaties en veiligheid van deze voertuigen.

Interne krachten en het zwaartepunt

Internal forces and the center of gravity are fundamental concepts in mechanics, playing a crucial role in understanding the behavior and stability of ...

Education

JoVE Core

Mechanical Engineering

Werktuigbouwkunde

Unit 1

Equilibrium of a Rigid Body

Evenwicht van een star lichaam

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

forces inside a body and balance

Internal forces and the center of gravity help explain how objects stay in balance. These mechanics ideas matter for structures, machines, and vehicles that must remain stable under different loads and conditions.

Internal forces are created inside a body when its particles interact. They can appear as tension, compression, or shear forces. These forces act in collinear pairs with equal magnitude and opposite direction. Between connected parts, they cancel each other and help keep the body in equilibrium.

A body’s weight is an external force. It is shown as one resultant force acting through the center of gravity. The center of gravity is the point where a body balances when no external force acts on it. For symmetrical or uniform bodies, this point is at the geometric center. For irregular or non-uniform bodies, it may shift toward the heavier side.

These ideas are important in civil engineering, mechanical engineering, and aerospace engineering. Engineers use them to design bridges, buildings, machines, vehicles, aircraft, and spacecraft that can handle wind, earthquakes, traffic loads, and other forces. If the center of gravity changes, the stability and safety of an aircraft or spacecraft can be affected.

Forces Inside a Body and Balance

conditions of equilibrium

Rigid Body Force Balance in Equilibrium

Rigid body equilibrium depends on a balance of external forces and moments. A rigid body is in equilibrium when it has no translational motion and no rotational motion. This happens when the net force and the net couple acting on the body are both zero. Internal forces are not used when checking equilibrium. These forces act in equal and opposite pairs inside the body, so they cancel each other. Because of that, they do not affect the overall motion or change in motion of the rigid body. The...

support reactions

Types of Structural Supports

Types of structural supports control how a coplanar force system moves and reacts under load. A coplanar force system is a set of forces that all lie in the same plane. The supports create reactions at the point of contact. These reactions help keep a structure stable under external forces. Supports work by stopping translation with an equal and opposite force. They can also stop rotation by applying a couple moment in the opposite direction. In structural design, these reactions are important...

internal forces and center of gravity

Internal forces and the center of gravity help explain how objects stay in balance. These mechanics ideas matter for structures, machines, and vehicles that must remain stable under different loads and conditions. Internal forces are created inside a body when its particles interact. They can appear as tension, compression, or shear forces. These forces act in collinear pairs with equal magnitude and opposite direction. Between connected parts, they cancel each other and help keep the body in...

alternative sets of equilibrium equations

alternative-sets-of-equilibrium-equations

Equilibrium Conditions for a Supported Plate

Equilibrium conditions for a supported plate are used to describe when forces and moments balance. In this state, the plate has no net movement and no rotation. Engineers use these equations to study how structures behave under external loads. In many cases, the standard equilibrium equations are enough. But some systems need an alternative set of equations to match the geometry of the support points. A rectangular plate supported at points A, B, and C is one example. For this plate, the...

two force member

Two-Force Body Equilibrium

A two-force body is a rigid body acted on by only two external forces. In equilibrium, those two forces must have the same magnitude, the same line of action, and opposite directions. This balance is what keeps the body at rest. For a plate with forces F1 and F2 applied at points A and B, equilibrium means the sum of moments about any axis is zero. If moments are summed about point A, the moment from F2 must be zero. That means the line of action of F2 must pass through point A. The same idea...

three force member

Solving a Three-Force Member Example

A three-force member is a rigid body acted on by three forces at three points. The forces must have concurrent lines of action. If the forces are parallel, their lines of action stay parallel instead. A dumpster provides the example used here. It is connected to a pin support at point A and to a pin on a hydraulic cylinder at point B. The hydraulic cylinder acts as a two-force member in equilibrium. The dumpster weight acts through the center of gravity, and the support reaction acts at point...

equations of equilibrium in three dimensions

equations-of-equilibrium-in-three-dimensions

Checking Force Balance in 3D Structures

Checking force balance in 3D structures is a key step when a system is at rest. The vector and scalar equations of equilibrium are used to test whether a body is stable and will not collapse or fall apart. These equations give a clear way to study the forces acting on a body. The vector equations of equilibrium require the vector sum of all external forces on a body to equal zero. They also require the vector sum of the couple moments and the moments of all forces about a point to equal zero.

support reactions in three dimensions

3D Support Types for Stability and Motion

Support reactions in three dimensions keep structures stable and in equilibrium. They stop unwanted translation and rotation, so a design can handle external forces safely and work as intended. These reactions are important in many structures and systems. A ball and socket joint is one support that allows free rotation about any axis. It does not provide a moment that resists turning. At the same time, it restricts motion in space with three reaction forces along the three dimensions. A...

constraints and statical determinacy

Constraints in Structural Equilibrium

Constraints in structural engineering control how a body can move and help keep it in mechanical equilibrium. A constraint is a restriction on motion. When the right number of constraints is used, the system can stay balanced with the fewest supports needed. A system with the proper number of supports is called statically determinate. In that case, the unknown reaction forces can be found from equations of equilibrium. These systems are the easiest to analyze and design because the forces can...

key terms and concepts

Learn how internal forces and the center of gravity affect balance, stability, and equilibrium in structures, machines, and vehicles.

Forces Inside a Body and Balance | 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

Forces Inside a Body and Balance

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