# Force: Two Body Scalar

Command ElementModifies a Force_Scalar_TwoBody force element.

## Format

<Force_Scalar_TwoBody
id                   = "integer"
i_marker_id          = "integer"
j_marker_id          = "integer"
is_action_only       = "boolean"
{
val                  = "real"
| val_expression       = "motionsolve_expression"
| usrsub_dll_name      = "valid_path_name"
usrsub_param_name    = "USER([[par_1[,...][,par_n]])"
usrsub_fnc_name      = "fnc_name"
}
/>

## Attributes

id
Element identification number, (integer>0).
i_marker_id
The ID of I marker.
j_marker_id
The ID of J marker.
is_action_only
A Boolean variable. Select from "TRUE" and "FALSE".
"TRUE": The element applies a force/torque on the I marker but no reaction on the J marker.
"FALSE": The element applies a force/torque on the J marker but no reaction on the J marker.
val
Modifies the magnitude of a constant valued force.
val_expression
Modifies the magnitude of the force vector as a function expression in the XML input file.
usrsub_param_name
The list of parameters that are passed from the data file to the user defined subroutine, specified by usersub_fnc_name.
usrsub_dll_name
Modifies the path and name of the DLL or shared library containing the user subroutine. MotionSolve uses this information to load the user subroutine in the DLL at run time.
usrsub_fnc_name
Specifies an alternative name for the user subroutine SFOSUB.

## Example

<Force_Scalar_TwoBody
id             = "30101"
type           = "Force"
val_expression = "2"
/>
<Force_Scalar_TwoBody
id             = "30101"
type           = "Torque"
val            = "2"
/>