It is an unbalanced force...consider this definition of a balanced force... Two forces that are equal in size and opposite in direction. Balanced forces have a net force of zero. Two forces exert the same amount of force on an object, causing no change in motion. Two equal forces give off the same amount of force on an object. . When 2 objects are balanced there is no motion. So when you hit the can of beans with a hammer, there is nothing on the 'other side' of the can of beans to balance that force so it is considered an unbalanced force. I hope this helps.