11. Two marbles are pressed together with a light ideal spring between them. but they are not attached to the spring in a any way. They are then released on a frictionless horizontal table and soon moye free of the spring. As the marbles are moving away from each other, discuss the following statements. [a] The momentum of the marbles are conserved. [b] The mechanical energy of the marbles is conseryed. [c] The kinetic energy of the marbles is conserved. 11A small wooden block with mass CLSIJI] kg is suspended from the lower end of a light cord that is 1.5 m long. The block is initially at rest. A bullet with mass 121] g is fired at the block with a horizontal turelocit'lr w]. The bullet strikes the block and becomes embedded in it. After the collision the combined object swings on the end of the cord. When the block has risen a 1.i'ertical height of {1.3 m, the tension in the cord is 4.3 N. 1ii'il'hat was the initial speed sin of the bullet