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Sci Tech
Ice covered road
PHOTO: AP
Will driving on an ice covered road require less fuel due to reduced friction?
K. S. NAIR
Thiruvananthapuram, Kerala
During acceleration the thrust (power) developed by the engine of a vehicle to propel itself is effective to the extent of the grip that the tyres of the vehicle have on the road surface over which it moves.
This grip depends among other things, on the friction between the tyres and the road surface. The greater the friction the better is this grip. The better the grip, the greater the utilisation of the thrust developed by the engine.
Slip, or the loss of grip, results in loss of thrust (power). This loss of thrust (power), is dissipated as frictional heat, not only in the mating surfaces between the tyres and the road, but also in the axle-bearings and other moving components of the vehicle. This results in wastage of fuel.
When the vehicle moves steadily (at constant speed), there is also the sliding friction between the tyres and the road surface, which retards the vehicle’s motion, and needs engine power ( and hence, fuel ) to be overcome.
Now, with ice covering on the road, acceleration will entail greater expenditure of energy, and hence more fuel, as the process becomes less efficient due to loss of grip.
The sliding friction will, however decrease due to reduced friction between the ice surface and the tyres, and requirement of fuel will be lesser.
Therefore, presuming that other conditions like the windage (friction due to air), wind force are all the same, and that the ice-sheet is not uneven, one may say that fuel requirement could be lesser on an ice covered road due to reduction in the sliding friction.
However, if there are innumerable stretches of accelerations/braking over the journey, this advantage of reduction in fuel could get lessened. It should also be remembered that vehicle manoeuvrability becomes difficult on an ice surface due to reduced friction.
Hence, operations of braking/acceleration will be prompted more frequently, say even during the small-degree steerings.
K. PASUPATHI
Professor of Electrical Engineering(Retd)
Eritrea Institute of Technology, Asmara, Eritrea
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