10. A force is applied to an object which undergoes a displacement. What can you conclude if the work done on the object by the force is zero? 11. Can a normal force on an object ever do work on the object? Explain. 12. Give a scenario where both positive and negative work are done on an object at the same time. 13. Give an example of a scenario where energy is not conserved, but momentum is conserved, and a separate example where both energy and momentum are conserved