67) If an unsupported uniform cross sectional elastic bar is subjected to a longitudinal impact from a rigid bob moving with velocity v, then a compressive wave of intensity sc is propagated through the bar as follows

68) Tensile strength of a mild steel specimen can be roughly predicted from following hardness test

69) Resilience of a material is important, when it is subjected to

70) In the case of an elastic bar fixed at upper end and loaded by a falling weight at lower end, the shock load produced can be decreased by

71) Other method of reducing shock load in the above case can be