sentences: the water pipe freezes & freezing is a kind of phase change ->  the water pipe undergoes a phase change  the water pipe undergoes a phase change & a phase change is a kind of physical change ->  the water pipe undergoes a physical change when it freezes  an example of a physical change is breaking an object & cracking is a kind of breaking ->  an object cracking is a kind of physical change  an object cracking is a kind of physical change & a water pipe is a kind of object ->  the water pipe cracking is a kind of physical change  the water pipe undergoes a physical change when it freezes & the water pipe cracking is a kind of physical change & a water pipe freezes and cracks on a cold night ->  the water pipe freezing and cracking is an example of physical change  the water pipe freezing and cracking is an example of physical change & chemical change is the opposite of physical change -> the water pipe freezing and cracking is an example of physical change but not a chemical change