Add an instant force impulse to the rigidbody, using its mass.

Apply the impulse force instantly with a single function call. This mode depends on the mass of rigidbody so more force must be applied to push or twist higher-mass objects the same amount as lower-mass objects. This mode is useful for applying forces that happen instantly, such as forces from explosions or collisions. In this mode, the unit of the force parameter is applied to the rigidbody as mass*distance/time.