ParticlePendulumFma.html  (MotionGenesis input/output).
```   (1) % MotionGenesis file:  ParticlePendulumFma.txt
(2) % Problem: Particle pendulum with air resistance.
(4) %------------------------------------------------------------
(5) NewtonianFrame N            % Earth
(6) RigidFrame     B            % Massless cable.
(7) Particle       Q            % Particle at end of cable.
(8) %------------------------------------------------------------
(9) Q.SetMass( m = 100 kg )
(10) Constant  g = 9.8 m/s^2     % Earth's gravitational acceleration
(11) Constant  L = 50 m          % Cable length
(12) Constant  bAir = 2.0 N*s/m  % Air-resistance constant
(13) Variable  theta''           % Pendulum swing angle
(14) Variable  Tension           % Tension in cable.
(15) %------------------------------------------------------------
(16) %       Rotation and translation kinematics.
(17) B.RotateZ( N, theta )
-> (18) B_N = [cos(theta), sin(theta), 0;  -sin(theta), cos(theta), 0;  0, 0, 1]
-> (19) w_B_N> = theta'*Bz>
-> (20) alf_B_N> = theta''*Bz>

(21) Q.Translate( No,  -L*By> )
-> (22) p_No_Q> = -L*By>
-> (23) v_Q_N> = L*theta'*Bx>
-> (24) a_Q_N> = L*theta''*Bx> + L*theta'^2*By>

(25) %------------------------------------------------------------
(26) %       Contact and distance forces on Q.
(27) Q.AddForce( -m*g*Ny> + Tension*By> - bAir*Q.GetVelocity(N) )
-> (28) Force_Q> = -bAir*L*theta'*Bx> + Tension*By> - m*g*Ny>

(29) %------------------------------------------------------------
(30) %       Form equations of motion with  F = m *a
(31) ZeroFma[1] = Dot( Bx>,  Q.GetDynamics() )
-> (32) ZeroFma[1] = m*g*sin(theta) + L*(bAir*theta'+m*theta'')

(33) ZeroFma[2] = Dot( By>,  Q.GetDynamics() )
-> (34) ZeroFma[2] = m*g*cos(theta) + m*L*theta'^2 - Tension

(35) Solve( ZeroFma,  theta'',  Tension )
-> (36) theta'' = -(m*g*sin(theta)+bAir*L*theta')/(m*L)
-> (37) Tension = m*(g*cos(theta)+L*theta'^2)

(38) %------------------------------------------------------------
(39) %       Initial values and numerical integration parameters.
(40) Input   theta = 60 deg,  theta' = 0 deg/sec
(41) Input   tFinal = 120 sec,  tStep = 0.1 sec
(42) %------------------------------------------------------------
(43) %       List output quantities and solve ODEs.
(44) OutputPlot  t sec,  theta degrees,  Tension Newtons
(45) ODE() ParticlePendulumFma

(46) %------------------------------------------------------------
```