Answer: The correct answer is "the same magnitude of force, 60 N should be applied".
Step-by-step explanation:
Balanced forces: These forces are balanced when the forces are acting equal in magnitude but opposite in direction. The balanced forces will not cause any change in the speed of the object.
Unbalanced forces: These forces are unbalanced when the forces acting on the object are not equal in magnitude. It will cause the change in the speed of the body.
In the given problem, Jennifer stands on one side of a filing cabinet and pushes with a force of 60 N. If Nathan wants to help Jennifer demonstrate balanced forces, then he should apply the same magnitude of force of 60 N.