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Edit Object Dialog 673
D yn amics Properties Material Editor rollout
The three spinners in the Dynamics Properties
rolloutintheMaterialEditorletyouspecify
surfacepropertiesthataffecttheanimationofan
object upon collision with another object. If there
are no collisions in your simulation, these settings
have no effect.
Because the Dynamics Properties rollout is
available at the top level of any material (including
sub-materials), you can specify different surface
dynamic properties for each face in an object.
There are also controls in the Dynamics utility that
letyouadjustthesurfacepropertiesattheobject
level, but only the Material Editor lets you alter the
surface proper ties at the sub-object level (through
use of a Multi/Sub-Object material).
As a default, the values in the Dynamics Properties
rollout provide a surface that’s similar to
Teflon-coated hardened steel. This is with values
of Bounce Coefficient equal to 1; with both Static
Friction and Dynamic Friction set to 0.
B ounce Coeff icient—Determines how far an object
bounces after pressing a surface (the higher the
value, the greater the bounce.) A va lue of 1
represents a bounce in which no kinetic energy
is lost.
Static Friction—D e termines how difficult it is for an
object to start moving along a surface (the higher
thisvalue,themoredifficultthemovement).If
something weighs 10 pounds and sits on Teflon (a
static friction of near zero), it takes almost no force
to make it move sideways. On the other hand, if it
sits on sandpaper, then the static frict ion might be
very high, around .5 to .8.
Sliding Friction—Determines how difficult it is for
an object to keep moving over a surface (the higher
this value, the more difficult for the object to keep
moving). Once two objects begin to slide over
one another, static frict ion disappears and sliding
frict ion takes over. Generally, sliding f riction is
lowerthanstaticfrictionduetosurfacetension
effects. For example, once steel star ts sliding over
brass (a value of static friction that might run
from .05 to .2), the sliding friction drops to a
significantly lower value: .01 to .1.
Edit Object Dial og
Utilities p anel > Utilities rollout > More button >
Dy namics > Dynamics rollout > Edit Object button > Edit
Object dialog
The Edit Object dialog is the main interface for
setting dynamic properties for any object in the
simulation. You assign dynamics properties one
object at a time. Select an object in the list under
Object,andthensetthatobject’sparameters.For
example, you can cause the object to b e affected by
gravity or wind, and specify collisions with other
objects.
Interfa ce