roblox-physics

name	roblox-physics
description	Constraints, VehicleSeat, ragdoll, projectiles, Attachment patterns, network ownership.
last_reviewed	"2026-05-27T00:00:00.000Z"
sources	["https://github.com/Roblox/creator-docs/blob/main/content/en-us/physics/mechanical-constraints.md","https://github.com/Roblox/creator-docs/blob/main/content/en-us/physics/mover-constraints.md"]

When to Load

Use this skill when building physics-driven gameplay: vehicles, ragdolls, projectiles, mechanical contraptions, elevators, swinging platforms, or anything using constraints and forces.

Quick Reference

Constraint Types

Mechanical: HingeConstraint (doors/wheels), PrismaticConstraint (elevators/pistons), CylindricalConstraint (telescoping), BallSocketConstraint (ragdoll/chains), UniversalConstraint (steering), WeldConstraint/RigidConstraint (rigid attach) Motion: AlignPosition, AlignOrientation, LinearVelocity, AngularVelocity, VectorForce, Torque Spring/Rope: SpringConstraint (suspension/trampolines), RopeConstraint (grapple, slack), RodConstraint (rigid link)

Attachment Pattern

All constraints connect via Attachment objects, not Parts directly. Create Attachment on each part, set constraint.Attachment0/Attachment1, parent constraint to part0. Actuator types: None, Motor (constant velocity), Servo (target position/angle).

Vehicles

Wheel = HingeConstraint (ActuatorType.Motor) + SpringConstraint for suspension. Steer = Hinge with ActuatorType.Servo. Rear wheels get throttle AngularVelocity, front wheels get servo TargetAngle. Use CustomPhysicalProperties on wheels for friction tuning.

Ragdoll

Replace Motor6Ds with BallSocketConstraint: create Attachments from motor.C0/C1, set LimitsEnabled=true, UpperAngle=45. Keep Root Motor6D for HRP. Set humanoid state to Physics. Re-enable motors to recover.

Network Ownership

Default: nearest player owns unanchored physics (exploitable!). part:SetNetworkOwner(nil) = server-owned (secure, laggy). part:SetNetworkOwner(player) = player-owned (responsive). Rule: NPCs/world objects → server. Vehicles → driver player. Always set explicitly on important physics objects.

Common Gotchas

• Constraints do nothing on Anchored parts
• Both Attachment0 AND Attachment1 required (missing one = silent fail)
• Over-constraining = jitter. Tune mass with CustomPhysicalProperties
• Use Raycast for hitscan, Touched only for slow physics projectiles
• Always set lifetime on physics projectiles (forgotten ones kill perf) Need more detail? Load references/full.md for the complete reference with code examples, API tables, and edge cases.