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Source: Roblox Creator Hub · CC BY 4.0 · View source · Code samples: MIT Imported 2026-10-03. Formatting adapted for this site.

PhysicsService

Inherits from: Instance → Object

PhysicsService primarily contains methods for working with collision groups which define whether a set of parts may or may not collide with parts in other collision groups. You can register a collision group through RegisterCollisionGroup() and assign parts to it by setting those parts' CollisionGroup property to the name of the collision group.

Creating, deleting, and modifying collision relationships between collision groups is limited to server-side Scripts.

See Collision Filtering for usage details in Studio and within scripts.

Inherits from: Instance

Memory category: Instances

Tags: NotCreatable, Service

Deprecated: This service has been deprecated in favor of per-world collision group configuration through WorldRoot which should be used for collision group management. Existing PhysicsService calls will forward to Workspace.

Methods

Name	Type / Returns	Description
PhysicsService:CollisionGroupContainsPart	boolean	Returns whether the part is in the collision group.
PhysicsService:CollisionGroupsAreCollidable	boolean	Returns whether the two groups will collide.
PhysicsService:CollisionGroupSetCollidable	()	Sets the collision status between two groups.
PhysicsService:CreateCollisionGroup	int	Creates a new collision group with the given name, and returns the ID of the created group.
PhysicsService:GetCollisionGroupId	int	Returns the ID of the collision group with the specified name.
PhysicsService:GetCollisionGroupName	string	Returns the name of the group with the corresponding ID.
PhysicsService:GetCollisionGroups	Array	Returns a table with info on all of the place's collision groups.
PhysicsService:GetMaxCollisionGroups	int	Returns the maximum number of collision groups.
PhysicsService:GetRegisteredCollisionGroups	Array	Returns a table with info on all of the place's collision groups.
PhysicsService:IsCollisionGroupRegistered	boolean	Checks if a collision group is registered.
PhysicsService:RegisterCollisionGroup	()	Registers a new collision group with the given name.
PhysicsService:RemoveCollisionGroup	()	Removes the collision group with the given name.
PhysicsService:RenameCollisionGroup	()	Renames specified collision group.
PhysicsService:SetPartCollisionGroup	()	Sets the collision group of a part.
PhysicsService:UnregisterCollisionGroup	()	Unregisters the collision group for the given name.

Inherited from Instance

Name	Type / Returns	Description
Instance:AddTag	()	Applies a tag to the instance.
Instance:children	Instances	Returns an array of the object's children.
Instance:ClearAllChildren	()	This method destroys all of an instance's children.
Instance:Clone	Instance	Create a copy of an instance and all its descendants, ignoring instances that are not `Archivable`.
Instance:clone	Instance
Instance:Destroy	()	Sets the `Instance.Parent` property to `nil`, locks the `Instance.Parent` property, disconnects all connections, and calls `Destroy()` on all children.
Instance:destroy	()
Instance:FindFirstAncestor	Instance?	Returns the first ancestor of the `Instance` whose `Instance.Name` is equal to the given name.
Instance:FindFirstAncestorOfClass	Instance?	Returns the first ancestor of the `Instance` whose `Object.ClassName` is equal to the given className.
Instance:FindFirstAncestorWhichIsA	Instance?	Returns the first ancestor of the `Instance` for whom `Object:IsA()` returns true for the given className.
Instance:FindFirstChild	Instance?	Returns the first child of the `Instance` found with the given name.
Instance:findFirstChild	Instance
Instance:FindFirstChildOfClass	Instance?	Returns the first child of the `Instance` whose `ClassName` is equal to the given class name.
Instance:FindFirstChildWhichIsA	Instance?	Returns the first child of the `Instance` for whom `Object:IsA()` returns true for the given className.
Instance:FindFirstDescendant	Instance?	Returns the first descendant found with the given `Instance.Name`.
Instance:GetActor	Actor?	Returns the `Actor` associated with the Instance, if any.
Instance:GetAttribute	Variant	Returns the value which has been assigned to the given attribute name.
Instance:GetAttributeChangedSignal	RBXScriptSignal	Returns an event that fires when the given attribute changes.
Instance:GetAttributes	Dictionary	Returns a dictionary of the instance's attributes.
Instance:GetChildren	Instances	Returns an array containing all of the instance's children.
Instance:getChildren	Instances
Instance:GetDebugId	string	Returns a coded string of the debug ID used internally by Roblox.
Instance:GetDescendants	Instances	Returns an array containing all of the descendants of the instance.
Instance:GetFullName	string	Returns a string describing the instance's ancestry.
Instance:GetStyled	Variant	Returns the styled or explicitly modified value of the specified property, or else the default property value if it hasn't been styled/modified.
Instance:GetStyledPropertyChangedSignal	RBXScriptSignal	Returns an event that fires when the given style property changes on the instance.
Instance:GetTags	Array	Gets an array of all tags applied to the instance.
Instance:HasTag	boolean	Check whether the instance has a given tag.
Instance:IsAncestorOf	boolean	Returns true if an `Instance` is an ancestor of the given descendant.
Instance:IsDescendantOf	boolean	Returns `true` if an `Instance` is a descendant of the given ancestor.
Instance:isDescendantOf	boolean
Instance:IsPropertyModified	boolean	Returns `true` if the value stored in the specified property is not equal to the code-instantiated default.
Instance:QueryDescendants	Instances	Returns an array containing all descendants of the instance that match the `selector` string.
Instance:Remove	()	Sets the object's `Parent` to `nil`, and does the same for all its descendants.
Instance:remove	()
Instance:RemoveTag	()	Removes a tag from the instance.
Instance:ResetPropertyToDefault	()	Resets a property to its default value.
Instance:SetAttribute	()	Sets the attribute with the given name to the given value.
Instance:WaitForChild	Instance	Returns the child of the `Instance` with the given name. If the child does not exist, it will yield the current thread until it does.

Inherited from Object

Name	Type / Returns	Description
Object:GetPropertyChangedSignal	RBXScriptSignal	Get an event that fires when a given property of the object changes.
Object:IsA	boolean	Returns true if an object's class matches or inherits from a given class.
Object:isA	boolean

PhysicsService:CollisionGroupContainsPart

Deprecated. This method has been deprecated. It's recommended that you query a part's collision group through its CollisionGroup property.

Returns whether the specified part is in the specified collision group. This method will throw a runtime error in the following circumstances:

The specified group does not exist.
The specified part is not a BasePart.

Parameters

Name	Type	Default	Description
name	string		The name of the collision group to check.
part	BasePart		The `BasePart` to check for membership in the collision group.

Returns

Type	Description
boolean	`true` if the part belongs to the specified collision group, `false` otherwise.

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:CollisionGroupsAreCollidable

Deprecated. This method has been superseded by WorldRoot:CollisionGroupsAreCollidable() which should be used for all new work.

Returns whether the two specified collision groups will collide. This method will also return true if either of the groups are unregistered, as the default collision mask collides with all groups.

Parameters

Name	Type	Default	Description
name1	string		The name of the first collision group.
name2	string		The name of the second collision group.

Returns

Type	Description
boolean	`true` if the two groups are set to collide, `false` otherwise. Also returns `true` if either group is unregistered.

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

PhysicsService:CollisionGroupSetCollidable

Deprecated. This method has been superseded by WorldRoot:CollisionGroupSetCollidable() which should be used for all new work.

Sets the collision status between two groups. This method will throw an error if either of the groups is unregistered, so it's recommended that you confirm each group's registration through PhysicsService:IsCollisionGroupRegistered() before making this call.

Parameters

Name	Type	Description
name1	string	The name of the first collision group.
name2	string	The name of the second collision group.
collidable	boolean	Whether the two groups should collide with each other.

Returns

Type	Description
()

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

PhysicsService:CreateCollisionGroup

Deprecated. This method has been superseded by RegisterCollisionGroup() which should be used for all new work.

Creates a new collision group with the given name, and returns the ID of the created group.

Parameters

Name	Type	Default	Description
name	string		The name of the new collision group to create.

Returns

Type	Description
int	The integer ID assigned to the newly created collision group.

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:GetCollisionGroupId

Deprecated. This method has been deprecated. It's recommended that you query collision groups by name through a part's CollisionGroup property.

This method returns the ID of the collision group with the specified name. It will throw an error if no group with the given name exists.

Parameters

Name	Type	Default	Description
name	string		The name of the collision group being retrieved.

Returns

Type	Description
int	The ID of the retrieved collision group, or `nil` if no such group exists.

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:GetCollisionGroupName

Deprecated. This method has been deprecated. It's recommended that you query collision groups by name through a part's CollisionGroup property.

Returns the name of the collision group with the corresponding ID, or an empty string if that ID (0–31) has not been assigned to a group. The method throws an error if the ID is outside the valid range.

Parameters

Name	Type	Default	Description
name	int		The integer ID of the collision group to look up.

Returns

Type	Description
string	The name of the collision group with the given ID, or an empty string if the ID has not been assigned to a group.

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:GetCollisionGroups

Deprecated. This method has been superseded by GetRegisteredCollisionGroups() which should be used for all new work.

Returns a table with info on all of the place's collision groups. Each value in the returned table is itself a table containing three members:

Member	Type	Description
id	integer	The ID of the group.
mask	integer	The collision group's mask; only for internal use.
name	string	The name of the collision group.

Returns

Type	Description
Array	An array of tables, each containing `name` (string), `id` (integer), and `mask` (integer) fields for a registered collision group.

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:GetMaxCollisionGroups

Deprecated. This method has been superseded by WorldRoot:GetMaxCollisionGroups() which should be used for all new work.

Returns the maximum number of collision groups the engine supports. This value is currently 32.

Returns

Type	Description
int	The maximum number of collision groups supported, currently 32.

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

PhysicsService:GetRegisteredCollisionGroups

Deprecated. This method has been superseded by WorldRoot:GetRegisteredCollisionGroups() which should be used for all new work.

Returns a table with info on all of the place's collision groups. Each value in the returned table is itself a table and containing two members:

Member	Type	Description
mask	integer	The collision group's mask; only for internal use.
name	string	Name of the collision group.

Returns

Type	Description
Array	An array of tables, each containing `name` (string) and `mask` (integer) fields for a registered collision group.

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

PhysicsService:IsCollisionGroupRegistered

Deprecated. This method has been superseded by WorldRoot:IsCollisionGroupRegistered() which should be used for all new work.

Checks if a collision group is registered. It's recommended that you call this method before calling methods that throw errors for unregistered collision groups, such as PhysicsService:CollisionGroupSetCollidable().

Parameters

Name	Type	Default	Description
name	string		The name of the collision group to check.

Returns

Type	Description
boolean	`true` if a collision group with the given name is registered, `false` otherwise.

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

PhysicsService:RegisterCollisionGroup

Deprecated. This method has been superseded by WorldRoot:RegisterCollisionGroup() which should be used for all new work.

Registers a new collision group with the given name. The name cannot be "Default".

Note that this method has a slight performance overhead based on the number of BaseParts in the workspace, so it's recommended that you register all collision groups at edit time through the Studio editor and call UnregisterCollisionGroup() and RenameCollisionGroup() as infrequently as possible.

Parameters

Name	Type	Default	Description
name	string		The name of the collision group to register.

Returns

Type	Description
()

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

Code samples: View on Creator Hub (PhysicsService-RegisterCollisionGroup).

PhysicsService:RemoveCollisionGroup

Deprecated. This method has been superseded by UnregisterCollisionGroup() which should be used for all new work.

Removes the collision group with the given name. If an invalid name is provided, this method will not do anything, although if the reserved name "Default" is provided, it will throw an error. If there are any parts in the collision group when it is removed, these parts will still maintain the same collision group ID. The physical behavior of parts in a removed group is undefined, so it is recommended to move any parts in a removed group to another group. This method will throw a runtime error in the following circumstances:

The name "Default" is provided.
The method is called from a client.

Parameters

Name	Type	Default	Description
name	string		The name of the collision group to remove.

Returns

Type	Description
()

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:RenameCollisionGroup

Deprecated. This method has been superseded by WorldRoot:RenameCollisionGroup() which should be used for all new work.

Renames the specified registered collision group, but does not rename the CollisionGroup property of parts that utilize the group. The first argument of this method is the name of the group to rename, the second argument is the new name for the group. If the specified group does not exist, this method will not do anything. The naming conventions for the new name follow the same rules as if the group was being created with RegisterCollisionGroup().

This method will throw a runtime error in the following circumstances:

Invalid or empty name provided for either argument.
The method is called from a client.

Parameters

Name	Type	Default	Description
from	string		The current name of the collision group to rename.
to	string		The new name for the collision group.

Returns

Type	Description
()

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

PhysicsService:SetPartCollisionGroup

Deprecated. This method has been deprecated. It's recommended that you set a part's collision group by name through its CollisionGroup property.

This method sets the collision group of the specified part to the group with the specified name. It is equivalent to setting the BasePart.CollisionGroupId, although calling this method is the recommended approach.

This method will throw a runtime error in the following circumstances:

The part parameter is not a BasePart instance.
The specified group does not exist.

Parameters

Name	Type	Default	Description
part	BasePart		The part being set.
name	string		The name of collision group that the part's collision group is being set to.

Returns

Type	Description
()

Field	Value
tags	["Deprecated"]
security	None
thread safety	Unsafe
capabilities	["Physics"]

PhysicsService:UnregisterCollisionGroup

Deprecated. This method has been superseded by WorldRoot:UnregisterCollisionGroup() which should be used for all new work.

Unregisters the collision group for the given name, with the following behaviors:

If an invalid name is provided, the method will not do anything.
If the reserved name "Default" is provided or if the method is called from a client, it will throw an error.
If there are any parts in the collision group when it is removed, those parts will still maintain the same collision group name. The physical behavior of parts in a removed group is undefined, so it's recommended to move any parts in a removed group to another group, such as the "Default" group.

Parameters

Name	Type	Default	Description
name	string		The name of the collision group to unregister.

Returns

Type	Description
()

Field	Value
security	None
thread safety	Unsafe
capabilities	["Physics"]
simulationAccess	true

Properties

Inherited from Instance

Name	Type / Returns	Description
Instance.Archivable	boolean	Determines if an `Instance` and its descendants can be cloned using `Instance:Clone()`, and can be saved/published.
Instance.archivable	boolean
Instance.Capabilities	SecurityCapabilities	The set of capabilities allowed to be used for scripts inside this container.
Instance.IsInSandbox	boolean	Indicates whether the instance is inside a sandboxed container.
Instance.Name	string	A non-unique identifier of the `Instance`.
Instance.Parent	Instance	Determines the hierarchical parent of the `Instance`.
Instance.PredictionMode	PredictionMode	Reflects the client-side prediction mode applied to the instance under server-authoritative physics.
Instance.RobloxLocked	boolean	A deprecated property that used to protect `CoreGui` objects.
Instance.Sandboxed	boolean	When enabled, the instance can only access abilities in its `Capabilities` list.
Instance.UniqueId	UniqueId	A unique identifier for the instance.

Inherited from Object

Name	Type / Returns	Description
Object.ClassName	string	A read-only string representing the class this `Object` belongs to.
Object.className	string

Events

Inherited from Instance

Name	Type / Returns	Description
Instance.AncestryChanged		Fires when the `Instance.Parent` property of this object or one of its ancestors is changed.
Instance.AttributeChanged		Fires whenever an attribute is changed on the `Instance`.
Instance.ChildAdded		Fires after an object is parented to this `Instance`.
Instance.childAdded
Instance.ChildRemoved		Fires after a child is removed from this `Instance`.
Instance.DescendantAdded		Fires after a descendant is added to the `Instance`.
Instance.DescendantRemoving		Fires immediately before a descendant of the `Instance` is removed.
Instance.Destroying		Fires immediately before (or is deferred until after) the instance is destroyed via `Instance:Destroy()`.
Instance.StyledPropertiesChanged		Fires whenever any style property is changed on the instance, including when a property is set to `nil`.

Inherited from Object

Name	Type / Returns	Description
Object.Changed		Fires immediately after a property of the object changes, with some limitations.