Sandy and Chris stand on the edge of a cliff and throw identical mass rocks at the same speed. Sandy throw her rock horizontally while Chris throws his upward at an angle of 45° to the horizontal. (i) Which one has a higher speed : Sandy’s thorwn rock at the launch or Chris’s rock when it reaches its highest point in its flight? (ii) Which one (sandy’s rock or Chris’s rock has the higher speed right before hitting the ground? : Explain carefully your answer.