What is likely to happen when molecule of ice begin to vibrate faster and faster? A picture from everyday life will help us here. What dose a boy do when he want a specially fine apple that is far out on a thin branch of the tree? He climbs part way up the tree and shakes the branch. The apples of the tree all shake violently backward and forward. swinging sharply on their stems. The extra motion makes them break their stalks and down they fall. Not only the one special apple. but many other as well. The stems were strong enough to hold the apples to the tree when they were relatively quiet. but the increased energy of motion causes them to break off. In much the same way. Single molecules escape from heated ice and flow away as liquid water.