The power of mass: inertial force

Lesezeit: 6 minutes

Aktualisiert am: 26.09.2025

Fachtexte von
Ladungssicherungs-Profis

The power of mass: inertial force

Inertia or inertial force plays an important role in calculating the forces that occur when transporting loads. As a value of acceleration, it is an element of the formula that allows the securing forces required for load securing and the number of securing devices to be used for this purpose to be calculated. In physics, inertial force or inertia is understood as the force that keeps a body at rest due to its mass and weight, even when external forces act on the body or mass. Its most familiar manifestations occur during acceleration and deceleration, as well as in the form of centrifugal force and Coriolis force. Coriolis force was derived from Newtonian mechanics. It can be used to explain physical flow phenomena such as ocean currents and wind currents.

Definition of inertia and inertial force

Inertial forces, also known as mass inertial forces, have the property of always acting against acceleration. They occur as actual forces in accelerated reference systems such as the Earth.

Table: Inertia force/mass force

All important forces of the mass forces to be considered at a glance:

in the direction of travel

Table for the minimum mass forces to be taken into account for normal driving conditions
zGM >	zGM up to 2.0 t	zGM >2 t up to and including 3.5 t	zGM > 3,5 t
mass force
0.9 FG	0.8 G		0.8 G
nach hinten	0,5 G	0,5 G	0,5 G
to the pages	0.7 G	0.5 G	0.5 G
The information highlighted in red deviates upwards from the basic rule VDI 2700-11/04. (Special feature of small vans)

Inertial force and reference frame

Inertial force occurs in all accelerated reference frames, even if no external force acts on the body. Accelerated reference frames are always in rotation or in some other form of accelerated motion. For example, the Earth's surface is a rotating reference frame because it is in constant rotation. The strength and direction of inertial force depend on the choice of reference frame and, in many cases, on location. In physics, the term reference frame refers to an imaginary space-time structure, conceivable as a three-dimensional coordinate system. In particular, the position and motion of physical bodies can only be specified relative to a reference frame. In inertial systems, on the other hand, a body at rest experiences no forces from other bodies and either remains at rest or moves in a straight line at a constant speed.

Laws of physics: inertial resistance and inertial force

inertial force

The basis for the assumption of inertial force or mass force in physics is that the motion of bodies is always linear and uniform when no external force acts on them. This assumption implies that a body at rest will remain at rest if no force acts on it. Rest is regarded as motion with zero velocity. However, when bodies are set in motion, their movement is no longer uniform and straight. This change in the state of motion is referred to in physics as acceleration. Inertial force is therefore the force that describes the motion of the body in an accelerated reference system. Inertial force does not occur in an inertial system, which is why it is sometimes referred to as an apparent force.

Examples of inertial force

As already described, centrifugal force is a form of inertial force. It occurs, for example, in a chain carousel, where the inertial mass is pushed outwards from the axis of rotation by a rotating system. In a lift, the inertia of the mass increases or decreases the effect of gravity. Inertial force also causes you to be pressed into your seat when a car starts or brakes. For a passenger on a train, the downward weight force of their body is added to the backward inertial or mass force. This gives them the feeling of running on an inclined plane. Gravity can also take on properties of inertial force. When the train brakes, standing passengers experience a sensation similar to the carriage tilting forward. Here, the force of gravity does not act vertically on the floor, but diagonally forward.

inertial resistance

The term inertial resistance refers to the resistance that a body accelerated by an external force opposes to this force. Inertial resistance can in turn be expressed by d'Alembert's inertial force. In d'Alembert's definition of inertial force, this complements the external forces to achieve a dynamic equilibrium. It is a consequence of the mass of the body and is therefore also called mass force or mass inertial force. This complement can be imagined as follows: mass and negative acceleration multiply to form a force that is equal in magnitude to the external force acting on the body.

Mass forces in load securing

If you imagine the loading area of a transport vehicle loaded with goods that can vary greatly in shape, material and weight and are exposed to different inertial forces during the journey, it becomes clear how important a professional securing system is to keep the cargo in place. Especially at high speeds, during acceleration, when cornering and during braking or evasive manoeuvres, heavy masses are set in motion, posing considerable risks to safe transport. As a result, mass forces, centrifugal forces and weight forces must be included as physical variables in the calculation of the required securing forces.

Massenkraft und Beschleunigung in der Formel für kraftschlüssige Ladungssicherung

In VDI 2700, which defines general rules for load securing, these forces are included in this calculation as an acceleration coefficient. As a general rule, 80 per cent of the total weight must be secured in the direction of the driver's cab and 50 per cent in the direction of the side walls and towards the rear. When driving downhill or braking hard, 0.8 times the load weight is pushed towards the driver's cab, and when cornering or starting off, around half the weight of the load is pushed towards the side walls and towards the rear. This allows the following simplified calculation to be made:

Load weight: 10,000 kg
Force in the direction of the driver's cab: 8,000 kg = 8,000 daN
Force towards the side walls and rear: 5,000 kg = 5,000 daN
Required preload force: 8,000 daN

This means that the required pre-tensioning force can be achieved with 20 lashing straps with a strength of 400 daN STF.

Sperrsysteme

Luft für individuelle Anpassungen

Mit unserem großen Sortiment an Sperrsystemen ist für jeden Anwendungsfall, wie z.B. in Transporten, Kofferaumbauten oder Wechselbrücken, immer die optimale Lösung dabei.