31. The noise level at 10 m from a long conveyor belt was 95 dBA. What is the noise level at 100 m?
32. A mine airway 2m wide, 2.5m high and 500m long. The airway passes a quantity of 8m3 per second. Calculate its pressure loss? Assume k = 0.0098 NS2m-4
33. A worker is exposed to 86 dB for six hours and 92 dB for three hours, giving a nine hour working day. Determine the dose % and TWA.
34. In a surface mine, sound pressure level at a location generated by operation of a dozer and a drill respectively are 80 dBA and 60 dBA, when operated independently. The sound pressure generated by the dozer compared to the drill is higher by a factor of
35. If velocity of air in a settling chamber is 0.3 m/s, terminal velocity of the particle is 0.19 m/s then find out h/I ratio of the chamber assuming eddy factor 0.5
36. A miner when doing hard work at 307 K may sweat at the rate of
37. A spherical droplet of water, with density 1000 kg/m3 and diameter of 1 μrn, is falling in air. The viscosity of air is 1.85 × 10-5 kg/m.s. Neglecting air density and assuming that the settling of droplet in air follows Stokes' Law, the settling velocity in m/s is
38. A single lamp placed centrally at the roof provides 40 lux illumination vertically below, at the floor of an underground workshop. The workshop of dimensions 20 m × 20 m with height 4m. Assuming uniform spherical dispersion of luminous intensity, the floor level illumination in lux at any corner of the workshop is
39. At a surface mine office the independent Sound Pressure Level (SPL) measured in dB(A) on account of 3 drill machines are 85,88 and 85. If all the three machines work simultaneously, the combined SPL, in dB (A) is
40. A filament bulb produces 30 lux illumination at point A as shown in the figure. Assuming that no other source of lighting present in the roadway, the illumination level in lux at point B will be
