3
rubber
rubber		1.5f
steel		0.5f
concrete	1.0f
rubber		1.0f
steel		0.25f
concrete	0.35f
steel
rubber		0.5f
steel		0.37f
concrete	0.45f
rubber		0.4f
steel		0.21f
concrete	0.32f
concrete
rubber		1.0f
steel		0.45f
concrete	0.5f
rubber		0.35f
steel		0.32f
concrete	0.25f
