Final answer:
The force due to friction on a stationary 40 kg box with given coefficients of static and kinetic friction is zero since no applied force is trying to move it.
Step-by-step explanation:
When a box of mass 40 kg rests stationary on a horizontal surface and no force is applied to move it, the force due to friction is zero. This is because friction, in this case static friction, only acts in response to an applied force that tries to move the object.
Since the box is stationary and no external force is attempting to slide it, the static friction force does not need to counteract any such force. Even though the coefficient of static friction is given as 0.40, it does not contribute to a frictional force without an opposing applied force.