A four-wheel truck or whose operating weight is 12000 kg , is pulled along a road having a rising slope of 2% at a uniform speed. Assume grade resistance factor = 10 kg/tonne. The tension in the tow cable is 720 kg. Then, the rolling resistance of the road will be:

Concept:

The rolling resistance of a road is calculated by subtracting the grade resistance from the total resistance acting on the truck. The total resistance is provided by the tension in the tow cable.

Given Data:

• Operating weight of the truck = 12000 kg (12 tonnes)
• Slope of the road = 2%
• Grade resistance factor = 10 kg/tonne
• Tension in the tow cable = 720 kg

Grade Resistance:

Grade resistance is given by:

\( \text{Grade Resistance} = \text{Grade Resistance Factor} \times \text{Weight} \times \text{Slope} \)

\( \text{Grade Resistance} = 10 \, \text{kg/tonne} \times 12 \, \text{tonnes} \times 2 = 240 \, \text{kg} \)

Rolling Resistance:

Rolling resistance is calculated as the total resistance minus the grade resistance:

\( \text{Rolling Resistance} = \text{Total Resistance} - \text{Grade Resistance} \)

\( \text{Rolling Resistance} = 720 \, \text{kg} - 240 \, \text{kg} = 480 \, \text{kg} \)

Rolling Resistance per Tonne:

\( \text{Rolling Resistance per Tonne} = \frac{480}{12} = 40 \, \text{kg/tonne} \)

The rolling resistance of the road is 40 kg/tonne.