Here's why:
* Physical Change: A physical change alters the form or appearance of a substance but doesn't change its chemical composition.
* Cutting Hair: When you cut hair, you are only changing its length and shape. The hair's chemical structure remains the same (it's still made of keratin). It's a change in the hair's physical properties (like length and style), not its chemical identity.
Here are some other examples of physical changes to hair:
* Brushing/Combing: Changing its arrangement and detangling it.
* Styling with Heat (curling, straightening): Temporarily altering the shape of the hair fibers.
* Wetting: Making the hair heavier and altering its shape.
* Braiding/Ponytails: Changing its arrangement.
* Adding Accessories (clips, headbands): Changing the appearance.
In contrast, here's an example of a chemical change to hair:
* Dyeing/Coloring: Changing the chemical composition of the hair to alter its color.
* Perming/Relaxing: Breaking and reforming the chemical bonds in the hair to change its texture.