Add project files.

Car simulation/WheelSystem.cs

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+namespace Car_simulation
+{
+    public class WheelSystem
+    {
+        // Physical properties
+        public float Radius { get; set; } = 0.3f; // meters
+        public float Inertia { get; set; } = 2.0f; // kg·m² per wheel
+        public int WheelCount { get; set; } = 4;
+        public int DrivenWheels { get; set; } = 2; // 2WD
+
+        // State
+        public float WheelEnergy { get; set; } = 0f; // Joules
+        public float AngularVelocity => GetOmega();
+        public float RPM => GetRPM();
+        public float Speed => GetSpeed();
+        public float ResistanceTorque { get; set; } = 0f;
+
+        // Calculations
+        public float GetTotalInertia()
+        {
+            return Inertia * WheelCount;
+        }
+
+        public float GetOmega()
+        {
+            if (WheelEnergy <= 0 || GetTotalInertia() <= 0) return 0f;
+            return MathF.Sqrt(2f * WheelEnergy / GetTotalInertia());
+        }
+
+        public float GetRPM()
+        {
+            return AngularVelocity * PhysicsUtil.RAD_PER_SEC_TO_RPM;
+        }
+
+        public float GetSpeed()
+        {
+            return AngularVelocity * Radius;
+        }
+
+        public float GetEnergyFromSpeed(float speed)
+        {
+            float omega = speed / Radius;
+            return 0.5f * GetTotalInertia() * omega * omega;
+        }
+
+        public void SetSpeed(float speed)
+        {
+            WheelEnergy = GetEnergyFromSpeed(speed);
+        }
+
+        // Apply work to the wheels
+        public void ApplyWork(float work)
+        {
+            WheelEnergy += work;
+            WheelEnergy = Math.Max(WheelEnergy, 0);
+        }
+
+        public void ApplyTorque(float torque, float deltaTime)
+        {
+            if (torque == 0) return;
+            float work = torque * AngularVelocity * deltaTime;
+            ApplyWork(work);
+        }
+
+        public void ApplyResistance(float deltaTime)
+        {
+            if (ResistanceTorque <= 0 || AngularVelocity == 0) return;
+
+            float omega = AngularVelocity;
+
+            if (MathF.Abs(omega) < 0.1f)
+            {
+                // Check if we have enough torque to overcome static friction
+                // For now, just return without applying resistance to allow startup
+                return;
+            }
+
+            float resistanceSign = -MathF.Sign(omega);
+            float alpha = (resistanceSign * ResistanceTorque) / GetTotalInertia();
+
+            float omegaNew = omega + alpha * deltaTime;
+
+            if (MathF.Sign(omegaNew) != MathF.Sign(omega))
+            {
+                omegaNew = 0;
+            }
+
+            float energyNew = 0.5f * GetTotalInertia() * omegaNew * omegaNew;
+            WheelEnergy = Math.Max(energyNew, 0);
+        }
+    }
+}