Add the following line into data/object.dat below the line that starts with "beachball".:
kb_golfball,		0.5,		0.00005		0.013,		0.25,		50.0,		0.0,  	2.0,    0, 	2,	1, 	0,	0,	0.0, 0.0, 0.0,		none
