Question about centre of mass and load centre of gravity

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Discussion Overview

The discussion revolves around the relationship between the center of mass and the load center of gravity in heavy vehicles, particularly focusing on their implications for vehicle acceleration and handling during directional changes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the effects on vehicle acceleration when the center of mass and load center of gravity do not coincide.
  • Another participant notes that generally, the center of gravity and center of mass are the same, but variations can occur in fields with significant gravity changes.
  • A detailed explanation is provided regarding the center of gravity (CG) as the point of equilibrium for a body, emphasizing its importance in vehicle dynamics, particularly in race cars.
  • The concept of mass centroid is introduced, explaining its relation to CG and how it can be visualized through sections of the vehicle.
  • The roll center of the suspension is described as a point affecting how the vehicle rolls under centrifugal force, with its position influenced by suspension geometry.
  • A later reply suggests that while the difference between CG and load center of gravity may not significantly affect acceleration, it could lead to unpredictable control during rapid directional changes.

Areas of Agreement / Disagreement

Participants express differing views on the impact of the center of mass and load center of gravity on vehicle dynamics, particularly regarding acceleration and control. There is no consensus on the extent of these effects.

Contextual Notes

Some assumptions about the conditions under which the center of mass and load center of gravity are considered may not be fully articulated. The discussion also touches on complex interactions within vehicle dynamics that are not completely resolved.

Who May Find This Useful

This discussion may be of interest to automotive engineers, race car designers, and individuals studying vehicle dynamics or physics related to motion and forces.

aabgenay
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Can anyone tell me that if centre of mass and load centre of gravity of a heavy vehicle doesn't concide,what vl be its effect on vehicles acceleration?
 
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generally the center of gravity and the center of mass is the same. However, if you are in a field where gravity changes significantly from 1 point to another, then it would be 2 different values.
 
Center of Gravity (CG) is defined as that point about which, if the body were suspended from it, all parts of the body would have equilibrium ..i.e.. without tendency to rotate. it is the 3D balance point of the race car. all acceleration forces acting on a body can be considered to act through the CG of that body..we have the cg to be as low as we can get it.

Mass Centroid- is related to Cg ..sort of...ifin we slice the car into a series of sections, like a loaf of bread, each slice would have its own CG...if, in a side view, we draw a line connecting each sliced CG..we have the Mass Centroid Axis..not really a straight line but close to it.
it gives an indication of the distribution of the vehicles mass in the vertical plane.

Roll Center of the suspension is that point , in the traverse plane of the axles, about which sprung mass of that tend of the vehicle will roll under influence of centrifugal force. It is determined by drawing a line from the tire contact patch to a point in space that is the intersection of the upper and lower suspension arm linkage angles.

The CG and RC are located at different points. Usully the CG is many inches above the RC. CG can be change by moving " weight " around on the chassis.. The RC is changed by modifying how the upper and lower control arms mount to the chassis. Correct changes will improve the weight transfer to the rear tires thus improving traction.
lot of other stuff goin on here.. race car math of some is on my post in General Physics post " Race Car Physics" 31 Dec 2008
 
Last edited:
aabgenay said:
Can anyone tell me that if centre of mass and load centre of gravity of a heavy vehicle doesn't concide,what vl be its effect on vehicles acceleration?

Ask a truck driver. It won't have much effect on acceleration. But control during rapid changes in direction can get a little unpredictable.
 

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