for example, once an egg has been fried, it cannot ever go back to its original form.
a physical change happens when a substance changes form but keeps the same chemical composition. the change can be reversed by taking away the cause of the physical change. salt water is a good example of physical change. once the salt and water have been separated, both objects go back to their original states. folding paper is another example of a physical change. the paper changes form, but its chemical composition stays the same.
sometimes, it may be hard to tell if the change that has taken place is physical or chemical. melting ice cream 