A block of mass M and a block of mass 3M are connected by a string, as shown above. The blocks are held with the string horizontally and are released from rest at the same time from a height H above the ground. How does the acceleration of the center of mass of the system compare to the acceleration of the object of mass M ?

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

answersysvol bloat;

the moving of the box is a result of centripetal force. think of that  as a car or a truck in this case creates a turn, the force of friction performing upon the turned wheels of the car runs centripetal force obligatory for circular motion for the things inside it.