Two Objects Interact with Each Other and with No Other

question 9

Multiple Choice

Two objects interact with each other and with no other objects.Initially object A has a speed of 5 m/s and object B has a speed of 10 m/s.In the course of their motion they return to their initial positions.Then A has a speed of 4 m/s and B has a speed of 7 m/s.We can conclude:

• A)the potential energy changed from the beginning to the end of the trip
• B)mechanical energy was increased by nonconservative forces
• C)mechanical energy was decreased by nonconservative forces
• D)mechanical energy was increased by conservative forces
• E)mechanical energy was decreased by conservative forces