Question:  I’m trying to accelerate a vehicle in reverse in EDSMAC (or EDSMAC4, EDSVS or EDVTS). I can get the vehicle to start with an initial velocity backwards, but when I provide throttle inputs, the vehicle changes direction and starts accelerating forwards instead ofaccelerating in reverse. What do I do?

In the physics programs EDSVS, EDVTS, EDSMAC and EDSMAC4, the throttle inputs are for forward acceleration of the vehicle.  That forward acceleration input overcomes the initial rearward velocity of the vehicle and results in the vehicle changing direction and accelerating in the forward direction.  In the physics programs EDVSM, EDVDS and SIMON, the user can use the drivetrain model to put the transmission of the vehicle into reverse, so that any throttle inputs (at the pedal) result in the vehicle accelerating in reverse.