Every object affected by gravity has a centre of gravity (COG), which is the point around which the object, if placed on a pointed stick in the ground, would be balanced in all directions. The higher COG, the more unstable the object (such as a truck) will be. The closer to the ground, the more stable the object. The stability of the truck is largely dependent on the height of its COG above the ground. If a load is not centred across its width the stability will be reduced when cornering. If the load is not balanced correctly along its length, wheel lock up during braking becomes a distinct possibility.
Kinetic Energy
Kinetic energy is the energy present in any moving object. The heavier and/or faster the object, the more energy it will contain. A bullet for example, is small but extremely fast and has the potential to do a lot of damage over a small area owing to its Kinetic energy. A Truck, on the other hand, is relatively slow but is extremely heavy and has the potential to do a great deal of damage over a greater area for the same reason. While a bullet’s energy is either absorbed by the target or eventually eliminated by friction as it moves through the air, the energy in a vehicle is converted to heat by the friction that occurs in the brakes when the driver applies the brakes.
1. Braking The faster a vehicle goes, the further it takes to stop As the table below shows, if a truck’s speed is doubled it will take at least four times the distance to stop. Longer if the road is wet.
Truck Speed
Road Conditions
Stopping Distance
Weight
40,000 Kg 40,000 Kg 40,000 Kg
35 Km/h
Dry
9 Meters
70 Km/h
Dry
37 Meters
70 Km/h
Wet
72 Meters
2. Cornering If a truck enters a corner at 60 Km/h (37.2 mph), there will be four times more overturning (side) force on the vehicle than if it had entered the corner at 30 Km/h (18.6 Mph).
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