Table 2.

Average value of coefficient of restitution for 2, 3 and 4 mm sized glass balls with various block combinations at different impact heights.

Block	Surface Condition of Grain	Grain Size (mm)	Coefficient of Restitution Values
			h1 (mm): 155	217	300
			Vel (m/s): 1.74	2.06	2.43
Brass	Smooth	2	0.80	0.78	0.76
		3	0.79	0.77	0.76
		4	0.77	0.76	0.75
	Rough	3	0.74	-	0.72
Granite	Smooth	2	0.93 *	0.93	0.92 *
		3	0.95	0.95	0.95
		4	0.97	0.97	0.97
	Rough	3	0.87	-	0.91
Rubber	Smooth	2	0.38 *	0.37	0.37 *
		3	0.43	0.43	0.43
		4	0.46	0.45	0.45
	Rough	3	0.41	-	0.42

* Data after Sandeep et al. [22].