52) Which of the following surfaces will give highest rolling resistance for a rubber tyred vehicle

53) If the gross vehicle weight of a truck is 30 t and rolling resistance is 30 kg/tonne, then the tractive effort required to keep the truck moving at a uniform speed is

54) The grade resistance factor for an earth moving machine can be obtained by multiplying grade percentage by a factor approximately equal to

55) A wheeled tractor hauling unit is working on firm earth. The total loaded weight distribution of this unit is:Drive wheels: 25000 kgScraper wheels : 10000 kgIf the coefficient of traction for wheeled tractor on firm earth is 0.5, the rimpull which this tractor can exert without slipping is

56) A four wheel tractor 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. The rolling resistance of the road will be