Anew cannon was being developed in a science lab. the instructor wanted to do some testing of the cannon's ability to launch objects with different masses. the instructor used tennis balls and filled them with lead, rocks, and styrofoam. the fourth tennis ball had nothing in it. the instructor fired each tennis ball with the same speed and measured the kinetic energy of each over a period of one second. determine which tennis ball had rocks in it and explain. a) purple represents rocks because it has more mass than all the other objects. b) green represents rocks because it is not as dense as lead and would likely have less mass than lead. c) green represents rocks because the rocks would occupy less volume than lead but more than styrofoam. d) purple represents rocks because it traveled faster than all the other objects since it is less dense.