A rectangular mine airway of 2.0 m width and 2.5 m height has a bend with deflection of π/4 radian. If the radius of curvature of the bend is 4.0 m, the shoc...

A rectangular face of 2.0 m×2.5 m dimension is blasted with 20 kg explosive in a 1000 m long drive. One kilogram of explosive produces 2200 cm3 of nitrous...

To increase the resistance of a mine roadway by 1.5 Ns2m-8, the size in m2 of the regulator to be installed is _________.[rounded off to 2 decimal places]