'Adds a torque to the body.
Parameters
vec: Vector
Defines the torque vector. Can be any vector w.r.t any frame or
combinations of frame.
Example
This example adds a simple torque around the body\'s z axis. ::
>>> from sympy import Symbol
>>> from sympy.physics.mechanics import Body
>>> body = Body(\'body\')
>>> T = Symbol(\'T\')
>>> body.apply_torque(T * body.frame.z)'

def apply_torque(self, vec):

    if (not isinstance(vec, Vector)):
        raise TypeError('A    Vector    must    be    supplied    to    add    torque.')
    self.loads.append((self.frame, vec))
