49) If the excavation of earth is done manually then it costs Rs. 10 per cum. A machine can excavate at a fixed cost of Rs. 4000 plus a variable cost of Rs. 2 per cum. The quantity of earth for which the cost of excavation by machine will be equal to the cost of manual excavation is

50) Which one of the following surfaces will give highest coefficient of traction while using crawler track tractors

51) Rolling resistance of a wheel depends upon (i) Vehicle load (ii) Grade(iii) Ground conditions .Of these statements

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