static void RotationalDynamics()
{
//Giant block o' pre-defined variables
float rotation = 0; // rad
float angularVelocity = 0f; // rad/s
float angularAcceleration = 0; // rad/(s^2)
float momentOfInertia = .11809f; // kg*(m^2)
float time = 0; // s
float deltaTime = .01f; // s
int reportingFrequency = 10; // timesteps
Vector3D position = Vector3D.zero; // m
Vector3D linearVelocity = Vector3D.zero; // m/s
Vector3D linearAcceleration = Vector3D.zero; // m/(s^2)
Vector3D massOneLocalPosition = new Vector3D(-.28f, 0f); //m
Vector3D massTwoLocalPosition = new Vector3D(.07f, 0f); //m
//Collect user input
Console.Write("Input the magnitude of the force in Newtons: ");
Vector3D force = new Vector3D(); // N
force.SetRectGivenMagHeadPitch(Convert.ToSingle(Console.ReadLine()), 30); //Set the rectangular coordinates of the force vector
Console.Write("Input the number of seconds the force will be applied for: ");
float forceDuration = Convert.ToSingle(Console.ReadLine()); // s
linearAcceleration = force * (1 / 6.1f);
float torque = massOneLocalPosition.X * force.Y - massOneLocalPosition.Y * force.X; // N*m
angularAcceleration = torque / momentOfInertia;
Vector3D massOneRotated = Vector3D.zero; // m
Vector3D massTwoRotated = Vector3D.zero; // m
using (StreamWriter writer = new StreamWriter("..\\..\\rotationalDynamics.csv"))
{
while (time <= forceDuration)
{
for (int i = 0; i < reportingFrequency && time <= forceDuration; i++)
{
//increment time
time += deltaTime;
//update position & rotation
position += linearVelocity * deltaTime;
rotation += angularVelocity * deltaTime;
//update velocities
linearVelocity += linearAcceleration * deltaTime;
angularVelocity += angularAcceleration * deltaTime;
//calculate mass positions relative to center of mass
massOneRotated = massOneLocalPosition.RotationAroundZ(Vector3D.Rad2Deg(rotation));
massTwoRotated = massTwoLocalPosition.RotationAroundZ(Vector3D.Rad2Deg(rotation));
//recalculate torque
torque = massOneRotated.X * force.Y - massOneRotated.Y * force.X;
//update angularAcceleration
angularAcceleration = torque / momentOfInertia;
//write data to file
writer.WriteLine(rotation + "," + position.X + "," + position.Y + "," +
(position.X + massOneRotated.X) + "," + (position.Y + massOneRotated.Y) + "," +
(position.X + massTwoRotated.X) + "," + (position.Y + massTwoRotated.Y));
}
//Display positions
Console.WriteLine();
Console.WriteLine("Angle: " + rotation);
Console.WriteLine("Center Mass: " + position);
Console.WriteLine("Smaller Mass: " + (massOneRotated + position));
Console.WriteLine("Larger Mass: " + (massTwoRotated + position));
}
}
}
